znode

Isp is constant no matter how many engines you add. Ultimately, ISP is a measure of efficiency - it's the ratio of force versus mass ejected, and is totally proportional to the exhaust velocity. That's a property of the engines, not how many engines you have. It's like firing bullets out of guns - no matter how many guns you have firing at the same time, it won't increase the speed of any of the bullets; it just means more bullets in the air at a time. What this means in practice is that dV does NOT go up with more engines, because your ISP stays constant - in fact, the more engines you add, the less dV you get, because the engines weigh you down. What adding engines give you is TWR at the cost of your dV.

Well, why not both? The field of bioastronautics has to develop sometime. Hibernation may not be "needed" for Mars, surely it's going to be needed for farther interstellar travel at some point.

You seem a bit optimistic. How old are you? What is your background in propulsions and rocket design so far? Are you with your local high-power rocketry associations? Have you participated in rocket launches?

What you're looking for is a ballistic missile trajectory, since you're looking for the most efficient sub-orbital ellipse that intersects with the ground at an arbitrary ground distance. Someone was nice enough to scan in the full copy of Bate, Muller, and White. Written by three professors of astronautics of the US Air Force Academy, this is literally the textbook on astrodynamics used by almost everyone everywhere, and contains all the math you'd need to suborbit, orbit, or transfer virtually anything anywhere in system, in real life. Equations will be on page 277 (pg 292 of the pdf), Chapter 6, ballistic missile trajectories.