So I thought my floor boards were pretty solid...It turns out I was mistaken...I got in it this morning after not driving it since friday and found a hole about an inch in diameter and the immediately surrounding metal quite soft. First off whats the best way to go about fixing this and what guage sheet metal should I use? as well when I go to weld it in place is there anything I should be worried about melting or heating? Thanks in advance

The best way I can think of to fix rust holes is to sand blast the
bad parts, hit it with some rust converter and then some no rust
paint. I took some polyurethane structural adhesive and glued the
metal into place, once cured the adhesive is really tough. You might
want to glue a piece of metal on to outside too so it's all sealed up.

Is this hole the drain that is on the floor or a real rusted hole?

Wild 

It's a real rusted through hole...Near where your left foot would sort of sit...Worst case scenario I go flinstones style I suppose...

ive cut and welded in patches on my truck (cut floor out of a crashed kick that didnt have rust, welded it in mine) perfect patch.
if your not a good welder its hard. its thin sheetmetal i burned a couple holes in mine before i got back in my groove. i welded patches for my larger holes and cut and fibreglassed my smaller holes. (trucks not a show queen, its a daily driver/weekend warrior)