volt vs amp?
First off i'll start with your last question lol it is a good idea to slow charge it for the first time after that u can peak charge it.
Each rechargeable battery usually has 1.2 volts unless it is a 9v battery lol or a lithium. each battery also has a certain mah like 600. then if u connect say 7 of those batteries + to - you get more volts (8.4) and still have 600 mah if u connect them all + to +, - to - you get 5600 mah!!! but only 1.2 volts. volts and mah will change with age when the battery gets worn out and with how full the battery is when it is completely dead it will have o,o full should be what the battery is listed at. or slightly higher.