XZebraEaterX

if you are moving from a vanilla server to tekkit, you won't lose anything, but some ores and worldgen things may be more scarce than normal because they'll only exist in new chunks

assuming you mean you are the one running the server, that is. if not, then the answer is yes you don't keep things from server to server.

Oh, and never backdate a minecraft world. If you are playing on 1.7 don't get tekkit because it's on 1.6.