This really should be in the FAQ.

For gearing, you need to work out what will work with your frame, chainrings and cog. Its best to start on a smaller gearing, say 42x16 or similar in gear inches (you may even want to start lower) and build up the strength. If you have hills you need to ride on a regular basis then go lower.

See:
http://www.sheldonbrown.com/fixed/index.html - for some good articles on building fixies.
http://www.63xc.com/gregg/101_1.htm - for a riders guide for newbie fixers.

Don't get a Suzue Jr hub, they're cheap and not very cheerful; quality varies widly. I would go for the Nashbar hub, which seems to be the same as the IRO, NYCB, Bens Bike etc. hubs that people are using. Nice sealed bearing unit that should last a lot longer than the Suzue.

The bars you're refering to are bullhorns/cowhorns. You can buy them (ie Chucks bikes has cheap $10 pairs) or cut drops to make some. Any brake lever should work. Some peeps use: BMX levers, standard road levers or TT levers etc. Go and look at the fixed gear gallery for some ideas (http://www.fixedgeargallery.com).