Hello @teju2friends, I can't tell you everything but here is what I think what fan be done.
1. I think it'll be multipage website. As not just the front page needs to be designed but the docs.question2answer.org also needs to be designed.
2. It can be your call, both are good.
3. Q2A also use free icons so there shouldn't be any issue with that.
4. Having a minimal design is best so white and blue color would be best choices. You can also add orange color since it is also there in Q2A logo.
Docs website is hosted on Github now, so you can see it here.
For the rest, only @Scott can tell.