If its the size of a dime that should mean only a few drops which isn't that bad for a 12 hour time span. I would be concerned [because im kind of meticulous when it comes to keeping my car in working order] but i wouldn't be panicked. Just periodically check your oil level and make sure you aren't low.
I know you said oil and i am assuming you mean engine oil, would i be correct in my assumption? We could help better if we were sure what kind of fluid it is and [more importantly] where its coming from.
And i can't help you with the window problem i am not experienced in that area sorry.
