I'm going to let the fuel question percolate for awhile. Meanwhile: antigravity.

If I expect to borrow Traveller starships, it's a given since none of them, or almost none, are set up for thrust-based "gravity" (e.g. "stack of tuna cans" deck layouts). This makes sense since jump isn't really thrust-based in Trav.

Technically it is for me, which is something to contemplate: why would you set up a ship so that your antigrav is always having to compensate for thrust at ninety degrees? Maybe a larger ship, that never lands on a planet and also has a larger cross-section, does align agrav with direction of travel. But if you're sitting on a planet for half(ish) your ship time, I guess airplane-like orientation makes more sense. If agrav can compensate for inertia, you don't have variable gravity as your acceleration changes.

I'm figuring antigravity is somewhat flexible. I've been noodling around with a little fiction writing in the gameworld, and one of the things that happens (spoiler!) is a wheel station catastrophic failure. With the loss of Coriolis force the wheel is in freefall, but a ship is capable of extending the gravity field far enough into the area around its lock to pull floating people toward it.

It is, though, an advantage tuna-can ships have, in that if they're docked nose-in to a station you just take an elevator down, whereas an airplane-type ship has a 90-degree gravity change in/around that airlock. So even if it doesn't have to adjust the pressure when docked to a pressurized station, it's going to have to "swivel" the gravity. Awkward.