Clever, but unlikely
In order for Catapult to work, it requires:
one object weighing 1 to 5 pounds within range that isn’t being worn or carried.
This is the requirement that Delayed Blast Fireball must meet. The question is: Does it?
Delayed Blast Fireball isn't explicit in the definition, but it does state:
A beam of yellow light flashes from your pointing finger, then condenses to linger at a chosen point within range as a glowing bead for the duration.
How much does a bead of light weigh?
In order for that bead to qualify for Catapult, it must be at least one pound and less than five pounds. As Dale M states, that's likely a DM call. But how should the DM approach?
Well, it's a beam of light that condenses into a bead. How much does a bead of light weigh? I'd think that a bead of magic light does not weigh anything, but another DM may believe otherwise. Then it's a question of does a bead of light weighs more than 1lb. Even if it did have a mass, it's unlikely to weigh more than 1lb.
Without meeting the weight requirement, you can't use Catapult to launch the Bead for extra damage (pending the save failure).
Throwing the Bead
There is another option for interacting with the Delayed Blast Fireball:
If the glowing bead is touched before the interval has expired, the creature touching it must make a Dexterity saving throw. On a failed save, the spell ends immediately, causing the bead to erupt in flame. On a successful save, the creature can throw the bead up to 40 feet.
This does imply that it can be handled, but it doesn't answer weight or anything else. Ultimately, this is a magic bead made of condensed light and it does not necessarily mean it has mass. It just means that you can throw the magic bead. If a DM does rule that it has mass, then it still needs to weigh more than 1 lb (see discussion above on weight of condensed light.)
Can you fire at an angle? Yes. Does it extend the range? No.
Catapult does not specify that the object flies horizontally. Nor are there any additional rulings from Sage Advice on the matter. Pick a direction and watch it fly.
But no matter what direction you point it, the range of Catapult is 90 feet, at which point it "falls to the ground". While it does not specify whether it full-stops or keeps going, the spell damage only applies to the 90 foot range.
A GM can homebrew that it would continue to sail and roll, but it would use a different damage system, no longer empowered by the spell. A good reference for rolling damage would be the Sphere of Crushing Doom trap from the trap UA, which is a 10 foot wide steel ball that rolls downhill, 150 feet in 6 seconds, and does 4d10 damage on impact with a creature. (Obviously a 10ft steel ball weighs a lot more than anything you could catapult, around 500lbs per cubic foot, so keep that in mind).
There's also the question of damage while the object is falling. This question has an answer that includes a GM-made nifty little chart a GM could use for falling damage.
In the case of a grappling hook or utility use, I'd probably put it to your DM whether it hard stops at 90 feet or not.
Best Answer
As you've noticed, the key sentence to deconstruct is the last one.
"In either case" refers to the case where the projectile is stopped by "stopping early if it impacts against a solid surface" versus the case where it is stopped by "the object strikes the target and stops moving".
Then the rest of the sentence is straightforward: "both [the object] and [the creature or solid surface] take 3d8 bludgeoning damage" - [the creature or solid surface] will refer to whichever stopped the projectile, and both that and the projectile itself will take 3d8 damage.