The spell creates fire and projects it away from you in a cone. The difference between this spell and, say, fireball, is that the fire is no longer magical once it's projected, and thus overcomes Spell Resistance.
Natural fires require fuel to maintain themselves for long. Once the spell is no longer maintaining the flame, it should quickly dissipate, assuming it wasn't cast into a field of dry grass or over a pool of oil. Note that lesser acid orb from Complete Arcane and Spell Compendium is also Conjuration(Creation) with an Instantaneous duration and creates neither an object nor a creature, simply a (non-magical, after leaving the caster) spell effect.
Orb of force is clearly meant to work like orb of acid, although this explanation is going to belong more on Physics.SE than RPG.SE. Force, in real world physics, is transferred between objects when they touch. Ergo, rather than "breaking" or "bouncing off", an orb composed entirely of force should be absorbed by a target (or by the ground or scenery on a miss) on impact. This is what does the damage of the spell - raw kinetic force being transferred to a relatively-stationary target.
Of course, the spell in this case probably shouldn't have the [Force] descriptor, as DnD [Force] has absolutely nothing to do with real-world force, as indicated by the fact that [Force] has full effect on incorporeal creatures and force should have none. If you (or your DM) want to rule orbs of [Force] continue to exist after striking a ghost or object, go for it. (However, both [Force] and force can be assumed to be weightless and noncorporeal, so rather than falling to the ground or filling a ball pit, they should probably keeping bouncing like that one scene in Men in Black until it escapes to outer space...)
Yes, cloning, repeatedly, maintained, could make you immortal.
There's some logistical concerns that make this trickier than the spell itself:
Vessel must be undisturbed
So, ideally, you set up a nice young version of yourself, hide it away for the time something goes wrong and go about your life, right? Well, the longer it's around, the more likely, over time, something COULD happen to it. Especially in a world where you've got things like purple worms, umber hulks and bulettes and other critters that dig through granite like butter.
Well, then it makes sense to set up some defensive measures, right? Traps, spells, etc. But in the world of D&D, the more defensive measures you put up, the more people assume it's got something valuable to steal...
Now, as a GM I wouldn't just automatically assume something is going to happen, but if the clone is sitting around for decades, or the wizard in question has enemies seeking them out, then we'd start having to think about problems.
A giant diamond
So, the diamond is worth 1,000 gp. This doesn't mean you can simply pull out 1,000 gp and find these diamonds anywhere, everywhere. There's got to be a limited number of them. You're probably not the only caster who is looking into this spell.
So, a bunch of wizards want immortality from a limited resource and are all looking for it.
I'm sure that's not going to lead to problems.
Welcome to the Immortal Club
So, if you manage to live far beyond even what most D&D world folks know people to be capable of, and you're known to be an awesome wizard... how many other people are going to be trying to get your secret of immortality from you?
How do other things which are immortal feel about this? Do they find a way to manipulate/play you because you're new to this game? Do they already have a control on the 1,000 gp diamonds and dole them out to the few wizards who have Clone just to keep them under their leash?
Is there an alliance of lichs who are jealous you've found a way to live, but actually live, not undead live, and they'd like to simply stomp you down for being audacious?
Are there mind flayers looking to eat the juicy mind of a super-intelligent wizard with 800 years of tasty-tasty knowledge?
Are there divine guardians of life and death who did their accounting and finding there's a soul short that needs to move on?
Gameplay
Unless you're playing a very unusual game of D&D, these issues aren't likely to come up too much simply because the timescale is too short. But it makes excellent source of adventures based on NPCs - just imagine what happens when you do have a wizard who has been doing this and dealing with all of these problems and what that means for the PCs when they get involved in it.
Best Answer
tl;dr:
What does clone do?
Clone:
How fragile is a clone?
D&D 5e doesn't have hidden rules, and spells do exactly (and only) what they say they do (see here, here, and here).
5e is also written using "plain English", so any term not specifically defined uses the standard dictionary definition. I can't find a D&D definition of "disturbed", so we have to use the dictionary definition:
and
So, what does it mean for the vessel to be "affected by interference" or "deviating from a normal condition"? The spell simply doesn't tell us.
A malevolent GM could rule that the "normal condition" of the vessel is the condition immediately upon completing the casting of the spell, in which case they could further rule that allowing it to become dusty would constitute "deviating from a normal condition". If your GM rules this way, find a better GM.
This GM's interpretation would be that disturbing the vessel would require an act that would likely damage the vessel. This could include an intentional action (eg., someone chooses to break it by hitting it with their sword), an accident (eg., carrying a vessel and failing a check, dropping the vessel), or - rarely - natural phenomena (eg., earthquakes). I stress that this GM would use natural phenomena rarely, since that (IME) gets awfully close to the "well, it's now dusty, so it's deviated from its normal condition" territory; there would need to be some kind of foreshadowing for this GM to resort to earthquakes.
A player who has a clone waiting for them at this GM's table would need to take some precautions against its being damaged. Putting the vessel in the vault of a reputable bank (à la Gringotts in Harry Potter) would probably be sufficient, as would the basement of their guild hall (... all parties have a guild hall, right? 😅); leaving it in the middle of the town square would ensure that it was disturbed prior to use (rotten teenagers 😁). Putting the vessel inside a larger box (with allowances for the caster to get out of said larger box, of course) would also be a good idea, though it might lose some of the "cool" factor.
This GM does tend to assume that the hard part is finding the vessel's location and getting to it. Disturbing the vessel is likely very easy to do once you get to it, unless the caster has provided additional protections (eg., magically hardened the vessel, used wards to prevent damage, etc.). It's like a heist: once you're in the vault, putting the diamond in your bag is the easy part.
All of that is to say: the GM has to determine what "undisturbed" means. As with all cases of GM rulings, it's best for the player and GM to work together to have a firm understanding of what "undisturbed" means in this context.
How does avoiding the material components affect things?
Wish is perhaps the most obvious way to avoid needing the material components, but I'm sure there are other options out there; "absolutes are always wrong", especially in D&D.
Anyway: if the caster has a way of avoiding the material components, how is clone affected? This GM has to conclude that wish would create a suitable vessel, though possibly one that is awkward to work with - it may form the vessel inside a handy tree, so moving the vessel would require moving the whole tree.
Show your work, minnmass.
Clone requires a vessel "that has a sealable lid and is large enough to hold a Medium creature", and the cloned body "forms inside a sealed vessel". It's implied that the vessel in which the cloned body forms is the one which the spell requires, but it's not stated explicitly. Further, the spell means that both a tiny a gargantuan creature would both require a vessel sized for a medium creature (that is, both a weasel and diplodocus would require a vessel sized for a human).
However, we do know that wish allows us to cast a spell without costly material components, and that the spell cast in that manner "simply takes effect". And, the effect of clone is that a cloned body "forms inside a sealed vessel". The most reasonable - and, indeed, only - interpretation that this GM can take is that wish would create a suitable vessel.