I am converting one of my old road bikes into a fixed gear but i don't know how to deal with the crank/chainrings. Should i just replace the whole setup? Also i am having trouble with the brakes, i replaced the original 27 1" x 1/4" wheels with just 27" ones so i am having trouble finding calipers with long enough arms to reach the smaller wheels. Any advice would be great as this is my first conversion project.
well, you could just leave it as is and only use one of the chainrings, but that's ugly and heavy and lame. if you feel like one of your existing chainrings is the right size, then take your cranks apart, remove the other two, and replace the long chainring bolts with single stack chainring bolts. otherwise, buy a new chainring of the appropriate size, and make sure it will fit your existing cranks. the cheapest ones are from rocket for $18.
fitting brakes on the smaller wheels will be a problem. there's not much (that i know of) that you can do, aside from keep hunting for a brake with long arms. ask your LBS, they might have some old used brakes that may work.
What drolldurham said about your cranks. If you like them, remove one chainring (if you have a double) or two chainrngs (if you have a triple) and get shorter chainring bolts. Generally, people use something like a 39, 40, or 42 tooth chainring.
I had a double crankset on my old conversion and after removing a chainring, they work great. See attached pic.
A trick I picked up is that you can flip your chainring around and use your regular chanring bolts without a problem. One side of your chainring probably has part of the hole recessed so that the chainring bolts fit, if you flip it, it won't have the recesses on the other side.
You should pick up some long reach calipers. Nashbar.com has these on sale now. Tough to beat the price for reasonable quality brakes.