1) u have 16 gig of ram, use 4 gig to tekkit, u will never use it all with teamspeak/mumble
2) yes u can do everything on linux via a ssh window eg terminal.
3) use winscp, it uses the same port as ssh and can send files aswell!
4)for tekkit u can do the config and upload it but i seemed to run into errors with it. eg conflicts on blockids.
5)details list of commands? google? linux teching class?