Re: Battery getting hot:
I am treating my battery like a baby. If you read about batteries in general and lithium batteries in particular you will find that: they should never get too hot, they should never get too cold, they should never stay discharged, they should never be stored in a cold or humid place. The battery should always be charged and the optimal temperature is about 20 Celsius. I learned this the hard way. Not paying attention to these details or being negligent will cost you $$ because your battery will suffer and you'll find out pretty soon because it will no longer hold charge, loose capacity, etc.
Also, I learned the hard way that a charger can lie and tell you the battery is charged (charging) while it's not. If you suspect this happens take action right away as running with a battery half discharged will ruin it. A voltmeter for checking the battery voltage periodically or whenever you see some strange behavior is the best thing.

Re: Battery being removed with a screwdriver
I haven't tried that myself and I don't recall the details but I believe both options are possible - forcing the battery off the bracket and forcing the bracket off the frame. I've heard that from two people and I believe it makes sense. Bike thieves can remove locks and chains that are pretty heavy, I don't see two rivnuts in an aluminum frame or a plastic lock being a problem for them.