Re: How many aikidoka?
As far as I know there's no aikido in Tibet. I was there (in western Sichuan, which is geographically, linguistically, and historically part of Tibet) and there were no formal active martial arts traditions in evidence. However, the people of Kham (the region of Tibet that I was in) have a reputation as fierce warriors, and I imagine they'd really enjoy aikido. I was only there for a few months, not long enough to start a dojo, but I thought about it.
And y'know, different sects of Tibetan Buddhists have been known to preach against each other, or at least engage in heated debates.