How to fix sheet metal holes?

My new (to me) Dart had trim strip down the sides, at the upper edge of the side panels. It also had a vinyl top once upon a time. Oh yeah, and a Torino hood scoop. The trim and vinyl roof was removed by the PO so I now have dozens of 1/4" holes in the sheet metal, leaking water in when it rains. One of my top priorities is to seal these up so I don't get rust going inside. So far, it looks like I have avoided a rust disaster.

Is there an effective way to seal these up on a temporary basis? The car looks like hell anyway so I'm just looking for something to tide me over till I can fix them right. I was thinking maybe cutting out little circles of duct tape? Haha, this would look like a teenager's first attempt at shaving with all the little band-aids all over... :steering:

Second question, how does one seal them up permanently? I think they can be brazed or welded then ground down? I am a horrific welder so brazing might be more my speed if it works. I think there is danger of warping the body panels if not done correctly? Any help is greatly appreciated.