So If I bought a 20 or 30 amp battery lets say for a sub ohm then I wanted too build a ohm level coil above 1 ohm's could I STILL use the same amp battery or do I have too get like a 10 amp as you stated above and ALSO does it matter what mah battery I get?
You can certainly use a 30 amp battery with normal resistance coils. You may not need the extra amps now, but it doesn't hurt anything.
Mah only gives an approximation of how long a battery will last between charges during usage. A not so accurate example is 100 mah is equal to 1 hour battery use. Generally speaking, the higher the mah of a battery, the less amps it will have. Likewise, the higher the amps rating, the less mah it will have. A couple of the newer hybrid/IMR batteries have both higher mah and amp rating, such as the Sony VTC 5. That's why its such a highly sought out battery for our application and so often hard to find available because of its popularity.
Pick your batteries by the application that you will be using them. If you need higher amps because you sub-ohm, then the higher amp batteries should be your priority, and higher mah becomes secondary. If you don't sub-ohm, then higher mah is the priority over higher amps. Just be sure you are using the right chemistry (IMR) for all of your battery needs, and not ICR.