The default theme should be minimalistic like the current theme. Nothing that looks "web 2.0": no speech bubbles, no significant space between posts, no significant hover effects, and few rounded corners.
This is surprising that I'm not left alone in this world, who hates the web 2.0 and XP style pokemonic interfaces.
The security, interface, functionality requirements are almost perfect and reasonable. The requests for moderation are too complicated. The standart moderation that by default is shipped with phpbb vbulletin or simplemachines is sufficient, if there is enough moderators available. With small staff moderating forum large as bitcointalk is like full-time job combined with slavery.
The requirement for blocking proxy or tor exit nodes is bad. I registered here when I was sceptical about future of Bitcoin, so I did not care to hide my IP or identity. OK, I'm not doing anything here on this forum that can give me meatspace trouble, but users should be left with possibilities to hide. If there is automatic flood and abuse prevention in place, such as limitation for users with few posts, there is little to no need for banning proxies. Still You cannot ban the proxies I offer as they all are run by many private users and they are not listed on web.