Constant acceleration is the holy grail of space travel. Right now it's gay and doesn't work. Currently, the more intense the gravity is in an area, the greater the effect of your thrusters in terms of your speed, which lets you go far. The term for this is "gravity assist" or slingshot, and it's why spaceships destined for the outer solar system always come close to multiple planets. They fire thrusters hard when they are close to each planet, and basically drift all the time between them.
A nuclear reactor produces heat. For space acceleration, you need to push something out one way to produce thrust in the opposite direction. Heat alone wont do much.
In theory yes, but there’s a lot of problems with the idea. To make it functional you’d want to shoot matter out at the most extreme speed possible. They have tried doing things like this but we aren’t technologically at a point where it’s worth bothering.
Askthually, firing your engines deep in a gravity well(essentially at periapsis) is called the oberth effect. It takes advantage of the higher kinetic energy potential. It's a distinct thing from just using a bodies gravity for a gravity assist.
Correct. Nuclear rockets use hydrogen for their fuel. Liquid hydrogen is ran though the reactor which vaporizes then super heats it then it's blown out a rocket nozzle for thrust. We've already built these and they're about twice as efficient as the best chemical rockets you can build.
I felt like giving him the names he'd encounter in TV shows for some reason, my bad.
This was recent and relevant:
