1) Most updated menus have the necessary files with them when you download the menu, just put them into your gta5 folder. If they are not included, search the forums here to find them.
2) ScriptHook was updated and prevented people from going into GTA Online with mods. However, people have cracked ScriptHook, and you are now able to go into GTA Online with mods.
3) Sorry I don't know too much about the differences either, I will get back to you when I know more.
4) I would personally mod my rp, that's about it. I would only do RP because it is not harmful to other players and it does not ruin the integrity of the game.(somewhat)
5)No, it does not reset your account if it is flagged by R*. The clear reports feature clears the reports that other players put against you, ONLY IN THE CURRENT SESSION. If you are trying to clear your reports from the session before your current one, it will not work.
Hopefully this helped you out, if you have any more questions, feel free to ask. I'll try my best to answer them.