seejohnbike

you're all fulla questions, aren't you, leslie?

anyway, google is your friend, and will give you many direct answers to these questions. also, sheldonbrown.com will answer a whole mess of these too.

as for 3/32 vs 1/8th cog, a 3/32 cog is great because it'll work with whatever chain you have already. however, I'd prefer 1/8th cogs and getting yourself a 1/8th chain, as most FG/SS stuff comes in 1/8th. unless you're REALLY splitting hairs, it doesn't matter, but just pick one, and stick with it, that way you'll always know what to look for in the future. You can run a 1/8th chain with anything, but if its a 3/32 chain, you need 3/32 cogs/chainrings.

with respect to the bike smith, i think I got my crankset from their ebay site. they're legit and shipping was quick, i think. However, the bike smith is a pretty common bike shop name, so I might be mistaken. In general, most online shops anywhere for anything are fine, it comes down to the speed of shipping and customer service.

you'll get the cog/lockring eventually, and considering the nature of them, you really shouldnt need any customer service. figure out if you want 3/32 or 1/8, and pull the trigger. the price is decent, so worst case scenario, you have to wait a week. no biggie.

edit: oh, also a new chain is only ~10, so worst case scenario, if you have to up your chain size, it'd be easier to grab something like a sram pc-1 from your lbs instead of shipping both ways/waiting for a different cog to come.

CardiacKid

Almost every lbs in the country sells Shimano freewheels and Surly cogs.
FWIW I run 48/18t fixed and 48/20 ss.