I don't know the answer to either question. I really just picked Alcor since at the time their Website looked far more professional than the alternative (although that has changed since). You can shoot the Alcor folks an email to ask about the membership: they're pretty good at responding.
I wrote an article about the process of signing up for cryo since I couldn't find any such accounts online. If you have questions about the sign-up process, just ask.
A few months ago, I signed up for Alcor's brain-only cryopreservation. The entire process took me 11 weeks from the day I started till the day I received my medical bracelet (the thing that’ll let paramedics know that your dead body should be handled by Alcor). I paid them $90 for the application fee. From now on, every year I’ll pay $530 for Alcor membership fees, and also pay $275 for my separately purchased life insurance.
http://specterdefied.blogspot.com/2015/04/how-to-sign-up-for-alcor-cryo.html