Yes, airsoft shells are refillable, being made of hard plastic and a hole to insert bb's in.
If you are referring to the gas-charged type, they can be reused many times.
yes but i recomend buying extra shells incase you lose them
I have never seen nor heard of a revolver airsoft pistol with non reusable shells. You should have no problems reusing them.
No, they can not, do not attempt to mix real ammunition in airsoft guns.
In all the airsoft revolvers I have seen each shell holds one bb for realism. Some also hold the gas to propel the bb, but most revolvers hold the gas in the handle.
They are allowed.
You have to take it apart
One can purchase airsoft revolvers at Hobbytron, Airsoft Station, and Air Gun Station online. Large retailers Walmart and Sears sell airsoft pistols and repeaters but do not carry revolvers.
None that I know of.