About Select Server our friend ADM-Devil has already posted some.
I also made available a Cabal Login Box.
Or if you prefer to do it yourself and know how to use photoshop, it's just to use MUimgGUI, convert the login_back and login_me files, and then you can login box the way you want it.
On opening 2 client 1 time only I tested here and there is no limit on how many Mu you can open at once, this is the criteria of how many your pc can handle, plus I open up to 3 and worked normal.