A new guy takes the plunge..., Advice welcome! Options

[pib]

So after a few helpful (IMG:http://www.914world.com/bbs2/html/emoticons/alfred.gif) from members this past week, I've started dealing with the rust on my '75.
I'm sure, as some have said, that this will turn into a complete resto (read: obsession), but I'm starting with the small stuff, and hoping to take what I learn from that into the bigger parts of the project.
I took a bunch of 'before' pictures, which I'll try to post at some point, maybe a blog...
First up, the trunks. Pictures are easier than a full description, so here you go: The red sled...

[pib]

That's really the worst spot, most of the rest was surface rust, and came off easily.
So now the questions...
I got my little box of goodies from POR-15 last week, and I could use some advice.
-How much do I need to brush/grind before using the Marine Clean?
- How the heck do you rinse it clean with water...just hose it down and then mop it up?
- Should I have the little hole welded up? Or can I just use the POR-15 filler product?
-I haven't bought a welder, or used one since high school, that's a few weeks down the line I think. Does anyone have a good recommendation for a home MIG setup? Or advice on what to avoid?

Thanks!
-Pete