Spoiler for SG Answers:
1. True ending of the game, which comes after Kurisu's ending.
2. Non. 15+.
3. Yes. There is adaptation by Yomi Sarachi (you can read it
here) and Steins;Gate Boukan no Rebellion - official spinoff about Suzuha.
4. She was revealed in fandisk of the game (Hiyoku Renri no Darling) and in Steins;Gate Boukan no Rebellion, you can read about her her
here.
5. It's being translated
here.
Found another Q & A about S;G:
http://ibm5100.net/steinswiki/2011/09/09/heroine-qgate/