Answer 1

Learn C++ and SDL. If you are new to this. A full fledged game engine is an extremely difficult task.

Answer 2

I am not ambitious enough to go for that lol. Writing and maintaining your own engine is a full time job. I mean you can write a small scale engine to handle your immediate needs but soon you need more so you write more etc etc. Tim Sweeny did however start with zzt and look where he is now. No guts no glory. Good luck my friend.