well it seems to be limited to you at the moment, as it works for me on your list. This captcha has been in use for over 10 years on many thousands of lists, this is the first reported issue I can recall.
no, not by default but you could create a plugin to do that.
that simply means, if a user buys premium membership, on new day you can add X hits to them which basically makes your premium members always show near the top at the start of a new day.
I was able to join your list and complete captcha with no problem. Perhaps you have a session issue with your browser, try closing your browser and start again.
http://visiolist.com/docs/styles-design
Changing Colors, fonts and other basic CSS properties
VisioList default skin "Parabola" (and hopefully all user contributed skins) include a user.css file which can be used to "override" the settings found in screen.css. This allows the skin developer to...