I believe my current understanding is correct, but I would just like to check that I've interpreted the rules properly...
1) Say I hyper from (20, -20) to (26, -20), and I know there are no star systems at either coordinates and no star systems in between coordinates... does that mean if I abort hyperspace, I can be 100% sure I will not destroy myself in a gravitational body?
2) Also, if I move from (20, -20) to (21,-20), and know that there is a star system at (21,-20) and I abort hyperspace... will I abort into (20,-20) with 100% surety that I won't destroy myself, or will I end up in (21,-20) and risk the chance of hitting a gravitational body there?
1) Yes. THe hyperspace crash thing is only when you pass through a system that has a planetary body in it. The course your ship takes through hyper is pre-determined when you start travelling.
2) At a guess, I'd say that it would take the entire length of period to travel that one square, otherwise there is the possibilty for cheating the system to get XP faster/get there sooner. This would also fit in with all the other forms of travel, where you simply arrive at the last square you were on. in which case you would be fine.