You get more updates if your registered, you can also view more of the site :3 We prefer if people join the site before because when it comes time for purchasing servers we are going to accommodate the number of members on the forum, if we have 1000 forum members buying enough space for 10000 people is a waste. So by joining before your helping us get an idea of the fan base size :3 You will also receive the notices when the game is released sooner, site members will be told first via a mass email to all members as well as a PM.
As for updates we put up as much as we can, but somethings don't make very interesting screenshots, like walls of code or messes of marking masks. There is also the factor that some parts of the game will be secret so it's a surprise when you play, when we work on those we can't exactly post progress pictures.
I'm not sure what will happen with registration, I mean in future if we encounter space issues we may close it for a time, or something like that. I can assure you though that we won't close it so only site members before hand are allowed in, that would be mean.
Also, I actually like blue the most, but I wanted to be different so all my PmC related stuff has a purple(indigo more like) theme ^^