Here are some short answers:
-They can't give back ascensions, so, at most you will get 100. However, the case is handled by mods individually and does not have a strict guideline. I've heard of mods kind enough to cheat through ascension to give it back. But also mods refusing to give any level back. Though, I've never heard anything about tek engrams. You probably will have to get them back yourself, but it doesn't hurt to try and ask kindly.
-Achievement are stored locally, all achievement stay unless you change computer.
-Imprints are lost. They can't do anything about it. But they sometimes (depends on the mod) offer replacements for lost dinos, but with random stats. But I guess you can raise a new batch.