Yes, most applications on a Mac are containerized to avoid one application from affecting (crashing) another. This also makes it easy to uninstall by simply dragging the application to the trashcan rather that having to run uninstall programs to delete residual scripts in other areas.
All windows files can play on a Mac if you run boot camp (which is bascially installing windows on your mac) if you want to run windows files on a native AMc operating system you must have the program installed for the mac version. For example, if you have Micrsoft Word for Mac then you can view files like .doc or .docx on your mac. Same with .wmp, you need window's media player installed on your mac. Hope this helps.
To the folder where you installed the game. My Computer ---> Program Files ---> Battlefield 2142 ---> around in there
No Internet provider comes installed on a Mac computer.
Windows software will not run on Mac. The Windows operating system will run on any Intel based Mac in dual-boot mode. You can use Boot Camp which is already installed on your Mac or another program such as Parallels.
Firefox is not installed with a new Mac it needs to be downloaded and installed. (See links below)
It could be a number of things, between an incorrectly installed application to something seemingly unrelated. If I were you, I'd try reinstalling it.
Mac OS Leopard
It depends on what language the program was written in and what you mean by "hack". If you have the Developer Tools (available from the Mac OS X installation disc) installed you will find otool in Developer/usr/bin/ If that is the kind of thing you are looking for you may want to try OTX - (see links below).
Not for the Mac but you can have the Windows 98 Hardware Disk installed on a Mac then download MapleStory.
Only if it came with iWorks installed or you bought it later.
Yes as long as your Mac has java installed
The Mac OS X Server software (See links below) can be installed on any modern Apple Mac computer or can be purchased ready installed on a Mac Mini ready to go.