Rear light - yes
Front light - no unless you're riding in really light traffic and need it for visability more than sight.
Tubes - I bought a bunch from Walmart recently when the LBS was closed on a Sunday in my suburban town. Work great, two dollars less. Also picked up a big ol' 32oz bottle of sealant for 6 bucks in the auto parts section. 700's too, don't know about thinner than 38c.
Shirts - I wear the 14 dollar Target running shirts, Duo Dry or something. I can't think of any complaint you'd have with them.
Gloves - come on...the 6 dollar weightlifting, aerobic, paintball gunning on and on and on gloves don't work as well as a 20+ pair of "bike" gloves?
Helmet - I agree with earlier posts: it's not so much the safety as comfort and temp.