I am super excited to see this project develop! Will you be accepting regular people as testers or only tech-savy people that are fimilar with the testnet and/or minecraft in general. As someone that hasn't played the game in a few years and that has never used the bitcoin testnet, I would still be interested in testing!
I believe I'll go for an open Alpha with bug bounties :-)
Also might be looking for donations, but won't start accepting any until at least a working prototype is out.
Plan to run regular contests for helping the server (community-voted most helpful member, most wiki contributions, most bug reports, etc) once the server is launched, plus an opening day tokens giveaway.