Alright, let's start saying that your assumption to apply real world physics to explain how unexplained spell effects work isn't going to work very well, specially in D&D/Pathfinder.
Now, Pathfinder has an two unwritten rules that say: "unless something says you can do it, you can't." and "specific rules override the ruling of the generic rule; and when lacking a rule, use the general ruling". As I said, those are unwritten (yet commonly accepted) but will help you a lot when reading things as written, and I need to mention them to further explain my case bellow.
Now, let's tackle those illusion spells that cause so much confusion at every table.
The spell description usually says what can be seen, anything else you should check the rules for Illusion in the Magic chapter, and if it can't apply, the general rules for spells (you would be surprised how many people actually incorrectly use certain spells by ignoring that).
Illusions says:
Illusion spells deceive the senses or minds of others. They cause people to see things that are not there, not see things that are there, hear phantom noises, or remember things that never happened.
Disguise Self is a glamer effect:
Glamer: A glamer spell changes a subject's sensory qualities, making it look, feel, taste, smell, or sound like something else, or even seem to disappear.
That said, we can see that even being an illusion, Disguise Self would actually make you feel like the illusion is real if you fail your saving throw. But in the case of Disguise Self, the part about tactile (touch) and audible (sound) perception isn't changed like normal glamers.
As for disbelieving it, Saving Throws and Illusions (Disbelief):
Creatures encountering an illusion usually do not receive saving throws to recognize it as illusory until they study it carefully or interact with it in some fashion.
A successful saving throw against an illusion reveals it to be false, but a figment or phantasm remains as a translucent outline.
Notice how glamer isn't listed here? So you don't get a translucent outline at all, it simply disappears to your character.
So, even if you can touch and feel the target if you reach out, the illusion works just as written, it doesn't clip into buildings, it doesn't fall into the ground, it doesn't levitate because the item is worn by a smaller creature pretending to be a large one.
How would an ogre feel when disguised as a halfling? If you tried to touch him you would feel something on the way (the ogre's body) and would most likely get a saving throw to notice the illusion and see the real ogre. But on a failed save, the GM could say you feel a force field protecting him (or something along those lines).
As for a dog wearing a hat of (animal) disguise, it would look like a normal person walking around, even dodging obstacles so the illusion can remain convincing. You would only get a saving throw if you tried to touch that person, or if the dog barked (a human barking? what is going on here...).
Why? Because the spell description does not say so. It isn't intended to do so; if that was the case they would have spelled it out to work that way.
The spell doesn't work like a hologram that has a fixed center of emanation and must be correctly placed or otherwise it would "look weird", because the spell is altering the senses of those who see it. For contrast, I believe the technology guide does have an illusion spell that works exactly like a hologram, by the way.
Happy gaming. :)
The spell does exactly what it says:
you can alter the appearance of structures,
or add them where none are present.
Creatures with truesight can see through the illusion
to the terrain’s true form; however, all other elements
of the illusion remain, so while the creature is aware of the illusion’s presence, the creature can still physically
interact with the illusion. (PHB5e p.260)
So, as written, you could make a 50 storey building and stand on the roof even if you can see it isn't real!
Similarly, you could lay down a 300 foot high wall.
What does can mean?
In the context "can" means the creature is able to still physically interact with the illusion. When taken with the fact the creatures without truesight (including the caster) must physically interact it clearly gives such a creature the option to treat it as physically there or not at its discretion. Whether this is a one off election or it can decide from turn to turn is a DM call.
Best Answer
Although I agree with the answer from cpcodes, I think it could be made clearer so I'll make an attempt.
The crux of the question is quite simple: does a "tactile" illusion include the ability to support weight? Clearly a tactile illusion could make metal feel like stone, but if an entire illusory object were tactile could you stand on it? It's possible that this isn't consistent, but Jeremy Crawford, the lead Rules Designer for D&D, has this to say:
While this isn't strictly identical to the proposed use of the spell, it is entirely unambiguous that mirage arcane is capable of producing illusions that support weight, and thus I conclude that an "illusion" of solid ground could be crossed regardless of what the "real" terrain was. All indications I can find are that creatures treat such terrain as if it were real regardless of any ability to "know" that it's not, and thus move at normal speeds.
As for making the affected area into a long path, I don't think that's possible. First of all, the spells I can find with malleable areas are quite explicit about it, but additionally the spell description does not say "one square mile". Instead it says:
"1 mile square" more closely follows the phrasing of areas like "20ft square", which I have never seen interpreted as "any shape with an area of 20 square feet", and instead it always means "a square shaped area with sides 20 feet long". This could have been made more explicit (using wording from some other spells, "an area contained within a 1 mile square" would be clearer), but I don't believe you could make a rectangle 2 miles long and 0.5 miles wide let alone a narrow 10 foot path 528 miles long.
You could still cross oceans with it because it isn't a concentration spell, but you will need to either:
be a School of Illusion Wizard (PHB p. 118) of 6th level or above - which would give you access to the Malleable Illusions feature:
This feature would allow you to, on getting to the end of your 1-mile illusory land bridge, alter the mirage arcane spell so that the land bridge now starts from where you are, and continues out to sea. Rinse and repeat for as many miles as you want to cross.