You don't
have to use the RPG stats on the minis cards if you're playing the RPG. Those stats are just a way for players (or DMs) to have a quick set of stats, if needed.
You can create your own character, using the character creation rules in the PHB and the DMG, and your character doesn't have to have the same stats as the card for a particular miniature. There are several different methods that you can use for creating your character (rolling dice for the ability scores, or "buying" the scores using a "Point Buy" system); talk to your DM to see which way he wants you to use.
Starting a character at a level higher than 1st level is, again, something that your DM should decide on (and, if he's going to let you start at a higher level, he should let the other players do the same).
Since you guys are just starting out, I'd highly suggest you start with 1st level characters...yes, they're more fragile, but it'll be easier to learn the game when you're starting out with fewer variables.
Well, your DM should really have one, though, if you guys have a bunch of minis with the stat cards, those stats may be enough for the DM to run the "bad guys".
(And, yes, your old avatar was the symbol of Bane...your new one is the symbol of Gond. The symbol for Heironeous is here:
http://www.wizards.com/dnd/images/dd_gallery/dd1/Heironeous_symbol.jpg )