The motor is delivered with a steel chainring from bafang. Don't know the tooth count for a m500 motor maybe other members can give you this information.
The chainring is mounted on a spider 104 bcd size so you can fit aftermarket parts no problem...
Yes i have ordered a e10 frame battery + motor directly so have several others on this forum. You just send a email to [email protected] specify what you want and where you are living and they will send you a quotation. More info is here in the forum just look for thé dengfu e10 threads...