Regarding the time it could take to travel between Earth and Mars, I recently saw a very interesting video on a concept called a "skyhook" that suggests it might be able to economically reduce the transit time to "just" two months or so, though I assume you'd still want to wait for an appropriate launch window, and in addition it probably wouldn't be operational in time to benefit the first few generations of travelers. :P https://m.youtube.com/watch?v=dqwpQarrDwk