Yeah, if you have facebook and aim on your battery drains faster. Also with wifi on as well. Remember you're coming from the no.1 battery life company in the world. If you get a selios 2600 you can last longer than the iPhone (no I don't work for them).
For the compass thing, just spin your phone around =) lol
And for the speed, well you can download govnah and set it to run at 1ghz all the time if you like. The Pre 2 runs an ondemand linux kernel profile by default, which scales to 300mhz when not needed. You can, without voiding any warranty, change that.
Also if you like to toy around you can install some new kernels that make it even faster.