Are these batteries you purchased yourself, they didn't come with the mod, right? I'm sorry, I'm just checking. How old are the batteries?
Do you mean what resistance build you should use? I'd say starting out if it's a single battery mod, 0.5--0.7 sounds safe, for the most part, but I'm far from an expert about it. With a single battery mod, though, you don't want to go crazy low resistance to start (someone can probably come by and put that much more eloquently and in terms you'd understand as far as Ohm's law, but you get the drift, I'm sure.) Also, you can use either wire but for mechs, most folks prefer Kanthal but you can use either....
Have you built an RDA before? Because what gauge of wire matters, too, in terms of building: if you know what you have, you could take a look at steam engine. org. In fact, I probably would. If I were to be building on a mech I would start with a simple build and maybe a single coil? With that said, you don't have to, if you are accomplished at building coils.
I am also prepared to be Wrong at All Times, and I'm not using a mech yet, though I am reading up on it some and um, you seem pretty non-specific about some stuff, which I very much hope you do know the answers to well, I'm going to leave the rest of this to the experts....
Good luck,
Anna