some cams have built in viewers. some you need to take the sd card out or take the cam back with you and connect them to the computer. i am able to put the sd card in my phone and view them that way. when you put in another card you should have an option to erase all pic's or format card. i allways do this to make sure i have enough room till next time. the one cam i have has a lcd screen that tells the % of battery left and total pics.
hope this helps