will the custom amatars be like creating your own character or still just basic photos?
I think at first they will just release the seasonal/holiday armatars at specific times, then in some time after they figure it all out they might allow us to create our own and use them.
how do you buy armatars with your armor points?
You don't buy armatars. If you're asking how to change it, then click "control panel" > "armatars" > scroll down then press "update armatar".