Hey, a couple of suggestions:

a. I can't find a way to sign up as a pure critic or a viewer - a user without a website.

There will be plenty of people (the category also known as end-users) who don't have a website yet who would still like to look at and review designs by other folks.

I wasn't able to sign up because my website is down for now.

b. It'd be nice to have a way to 'save' credit and expend it later on reviews for sites that I may build later.