4.5.0.99 is the latest official release available for your device at this time. There are probably beta devices available. You should be fine with .99.
I would recommend a BlackBerry data plan. The browser will not compare to that of the iPhone. You could install Opera Mini, it may suit you better.
Could you elaborate a bit more as to what you would like to do with your blackberry?
i want to use my email and use the internet like a basic computer..my only concern about getting internet is that the 8310 doesnt have wifi, and i dont want to wait forever to load pages