inshallah-means (roughly) god willing. In practical terms it means "I can't really commit to it." If I show up, I show up, and if I am late or don't show at all, its all on God. Don't look at me, I'm not in charge! It also is an accepted thing to add to any intention (even sincere ones) because Muslims are never supposed to falsely state something. So "see you tomorrow, inshallah" means, I intend to be there, but if I can't be, note, this is not a gurantee. I sure plan to be.
The different inshallah's are implied by the circumstance and the relationship. And of course, whatever you think it is, if it doesn't happen, then there was an out submitted at the outset.
Insha Allah, I will come back and see the rest of the thread.