Before giving up on the battery, drain it completely, then charge it to full capacity with the phone switched off, repeat this a few times and see if the battery gets any better.
As for the replacement battery, I am no expert but I don't see any problem with it
The Wireless problems I have also, I think it is because the phone's wireless antennae is quite weak for some reason, and cannot receive a strong enough signal to remain connected, although this is *just* a theory.
You may want to rethink the Bluetooth dongle, as the one you have chosen is NOT compatible with Bluetooth 2.0, so you will not be able to get the maximum connection between your device and the computer.
Hope this helped.