No you cannot.

You cannot really hear the audio to well on the camera when you play it back on, however its somewhat decent when you upload it and play it back.

Have had no problem with the battery door. It very secure but not hard to open to change batteries.

4

Near the very bottom, the memory card and the batteries go in the same little slide door. Be sure to press down hard or the battery door will not close.

Yes, my daughter has taken a few videos of her and her friends acting funny, they came out really good. She posts them on ther facebook.

you don't- it's just AA batteries- you can get the rechargable kind though...

The best quality pics will be set on ISO 800 and 8M. They take up more camera memory so are fewer. If you want to take lots of pics, set Size to 0.3 and ISO to 64 or auto. Keep playing with it until you find the right settings for your particular use. I like to use the best quality then upload them to my computer...then continue shooting. Get a memory card for sure!