Yesterday, I was in a t-mobile store picking up a car charger for my 8700g, and was told not to talk on the phone while i was charging the phone, that it will ruin the battery. Is this true? I thought this was only true for older batteries. Anybody know?

I have never heard this. I do it fairly regularly and have not noticed any problems.

I have not heard of that. I know you can't use your Bluetooth headset when it is charging but not your phone. In fact I charge my BB everyday, doesn't matter if it is low batt or not.

When I just got my 7520 back then, I read from one of those welcome emails you get when you just activate your phone that it is adviced to charge your phone for at least 10-15 minutes a day. I have read that charging your phone when it is almost down the drain takes LONGER to charge than charging it a few minutes everyday.