Top, looking at your pics..You will find welding much easier and better if both srufaces are bare metal...The spots you weled in the top photo, that pinkish panel should be bare steel fora bout 1" back from the edge you're welding. It keeps the weld free of cotaminants, and lets the metal cool (deal witht he heat) much easier than if it's painted. I'm not sure what the 2nd pic was, but on #3, the factory spot welds the 1/4 to the outer wheelhouse there. I cant see any signs of brazing, but maybe it's me/ It looks like a nivc factory welded 1/4 you cut off to me...lol.
I'm adding this pic. It'sa patch from en engine bay. You can see the fake "spot" type welds that will be ground down and look very close to factory when finished. Also, on the butt weld, you can see the small overlapping "dot" looking welds I do. It adds very little heat to the seam. The rust pits were all cleaned out and treated before etch priming.