Ive just removed the windscreensfrom my splitty bit of surface rust but not too bad. What would be the best way to paint this up before replacing the windscreens and also isnt there meant to be a drain hole in there somewhere?

i dont have a splitty but yes there should be a hole, best way is to take it back to bare metal or cut it out

Building funds for a bare metal resto but I've sanded most of the rust off and used rust converter on a few spots where it is a bit deeper now I want to seal and paint it and stick the screens back in so I can drive it for a couple of years until it all gets done properly.

you can do the small area or concern bare metal, all it takes is a bit more time on the sander, and or more paint remover, my advice is any spot you want to deal with take it all the way back and make it shine, probably 30% more time now and no hassles later and its not a cost issue if you take the time to sand it back

Ihave taken all the paint off but now what is the best paint\treatmentto use in what is allways going to be a wet area. Also where are the drain holes meant to be.