I am not really planning an elf per se, but if you are looking for a more lithe type of body and sharp ears, then I will have some picks for you later on!
Absolutely! You will be traveling the galaxy with them; there will be a lot of time to develop properly deep romantic relationships with them if you want. With some, it will be more difficult, but the entirety of the main cast will be ready for it.
As for how it will work, you can check my older posts itt for more details, but tl;dr version is that you will pick one main love interest (which will unlock special scenes with her), but you won't be punished if you decide to have fun with others as well. As Tessa says in the game: "Spacers share everything." This will obviously mean three/four/etc.somes, but if you want to focus on just one, you'll be able to.
It all boils down to what you want from the game; if you want to focus on just one love interest or slut around or something in between, everything will be feasible, and I won't be punishing players for either.
Non-linear, pretty much everything is optional. No grinding. No time limits unless warned repeatedly before!