When you strip it down to make it a fixed gear, do NOT butcher the frame and grind off the cable stops and derailleur hanger. That way, if you decide to later, you can put it back as a geared road bike.
Also, you'll want to learn how to keep a straight chain line, etc. I'd gear it about 42:16, which will give you in the neighborhood of 70 gear inches.....good for city riding, not too high, not too low. You could turn it into something along the lines of my Nishiki conversion fairly easily
I'm running Alex 700c x2100 rims with track hubs and 700x28 tires, and a single front brake. I ride on Eggbeater pedals because I outgrew clip and strap back in the 1970's when clipless was invented.