If you mean custom games you go into multiplayer and in the bottom righthand corner you should see the custom game section.
yes
no its free to play unlike world of warcraft
yes!
Star craft two is the next game in the Star craft series.
starcraft is a prequel to starcraft 2
It certainly is.
Star craft 2 is for the PC system, different types will work with MAC but you have to buy the compatible software.
yes, so it can save achievments to you online profile at battle net
from my point of veiw yes it is.
Absolutely.
If by skirmish you mean able to play AI in 1v1, 2v2, 3v3, and 4v4? Then, yes it does have skirmish.
because it is awesome