When I receive enquiries I now also invite people to check us out through independant sources. I supply the url's for both AikiWeb and E-budo and encourage them to ask questions about me, my sensei, the dojo, and organization. I also encourage new students to check out the other teachers in town. I tend to agree that when someone doesn't want you to see other classes it smacks of shadiness.
1. Verifiable rank: You can verify the rank with a legitimate (maybe mainstream is a better term) aikido organization
Hmmm, I don't know if I'd say mainstream. I don't think Seidokan is mainstream but I'd consider it a legitimate org. independant from Aikikai Hombu, I'm sure there are others.