good work on the patches. A few thoughts you might already be thinking about - take the paint removal out farther around the patches & run the filler out beyond the weld lines & feather to the body. Get rid of that other paint as much as possible, you can spread a large area of filler & when you start blocking it down it'll end up pretty thin but wide if done right. Your going to prime the whole thing anyways. Its OK to go over existing paint as long as its adhered properly to the car, any lifting at all & it needs to go first, Rough up w/80 grit & wipe with a wax & grease remover before applying filler.

Just some thoughts, keep at it - looks good!