Steel rims..

Try going to pawn shops and such. I found an old frame with a steel rear wheel. Best rim I've ever used.

Wide enough tire? IMO, no. I'd start at 2.125 which is about the max for many bike frames (like mine). By putting the biggest tire you can you smooth out the ride by not needing as much air pressure, slightly decrease the final drive ratio (increased speed) but you may see a decrease in overall power. But I also like the look of a fat tire on a narrower rim to give it that balloon tire look.

This was my bike with a schwinn 26x1.95 in the back


This is with my new Kenda Kruiser 26x2.125 in the back and the schwinn up front.


Based on what I've seen of the old boardtrack racers, I'd say the fatter tire looks better.

I would try to find the 1.75" wheel if you plan on running the larger tires avaliable these days. I have 3.0x24 tires on a build and the 1.75 rims are the way to go. If you are always going to run tires of the smaller sizes then the 1.5s are fine. I would favor the MTB wheels.