Re: Caulking windows
We pulled our windows out because when we first got the bus they had leaked quite a bit and we wanted to see what condition they were in. For Gustav, they are held in by four screws and sit on a ledge. Once out, we cleaned up the metal ledge they sat on (scuffed bare, then POR-15'd 'em). We decided to move our emergency exit windows (they not only open but also swing out) so that they were all together where we wanted to place our garden. Our windows had some simple weather stripping which we peeled off, cleaned up and applied new.
Then we did a simple water-check by taking a hose and pointing it in the air and letting the water fall back onto the bus as simulated rain. We could see water coming in, and after the big rust cleanup job, we decided that it wasn't good enough. After talking with several people, who claimed that a bus would never be rain proof, we decided to caulk from the outside of the bus along the edges where the weather stripping was. Creating a complete seal took 5 or 6 tubes of caulk, but in the end you can take a water hose and spray directly against the windows and there will be no leakage.
So to answer your question, we used Caulk as a way to keep rain and spray out of the bus, not to hold the window in place. The screws tighten down the window enough that it doesn't rattle in the slightest. As for pictures, I will see what I can find.