First of all, you can't get the WiFi service book from AT&T unless you have a BB data plan.
Second, since you are on AT&T, you might as well get the BB data plan now as they will add it as soon as they detect a BB on the network without the correct plan. Took them 26 minutes to see my 9000.
And finally, not going with a data plan really limits what you can do - no email, no facebook, no IM (at at least only limited choices), no BBM, no maps, no BB App World, and the list goes on. Any app or service that requires a connection to RIm will not work unless you have the data plan.
As for a 3rd party browser, there aren't many option, but Opera Mini appears to be the best. But from wmat I have read it is hit and miss also - some love it, some hate, some get it to work, others do not.
From our FAQ; What do I need a Data Plan for? - BlackBerryFAQ