Windows 7 will work on a recent Mac (See links below).
No, and using windows 7 is not legal
Mabinogi will work with windows XP and up (that includes vista, and 7 when it comes out). As for the mac, the only known way is to use bootcamp to run windows on your mac.
Yes, you need to install Windows 7 onto Bootcamp (which comes free with the mac) or parallels, which you can buy. Then you can boot into Windows 7 or Mac OS X.
You would need to hack it
Windows 7 is an operating system. A Mac is a computer. A Mac can run Windows 7. The two things are not comparable.
Windows 7 by a lot.
Games written for the Windows operating system require the Windows operating system to work. If the Mac has Windows installed on it then it will work otherwise it will not work.
Windows 7 is slower than the new operating system Lion for Mac. Windows 7 has most of the features all macs have had in the past and they are way behind everything the Mac does. In 5 years Windows will be doing the stuff Mac has just done this year. My advice don't buy Windows 7 you can buy a Mac and put Windows 7 on a Mac for like $100. And you get way more features on a Mac than on Windows 7. So basically Lion is way better than Windows 7. Hope this helps :)
Windows 7 can be installed on any Mac that has an Intel processor (See links below).
Windows games are written to work with the Windows operating system. The Mac does not use the Windows operating system and so the game will not be able to work on a Mac. You will need to install the Windows operating system on your Mac or some software that emulates the parts of the Windows system that the game needs to have a Windows game work on a Mac.
No you cannot, as Mac OS X is designed on the software base of Unix which is different to the base of Windows, It will not work, it will only work properly on Mac OS X
Games written for Mac OS X will work on a Mac. Games written for the Windows operating system will require the Windows operating system to be installed on a Mac to work. Some Windows games can be used on a Mac without Windows by using CrossOver Games software.