I certainly can't afford a Mac. How can I run Mac OS X on my Raspberry Pi 2?

The Raspberry Pi does not have the binary compatibility to the Intel architecture that Mac OS X requires.  So no, you cannot run OS X on your Pi.

Can Raspberry Pi 2 run the PS 2 emulator?

It should be able to run any Debian Linux PS2 emulator. However, the performance may very well be poor.

How to use Raspberry Pi 2 as a desktop PC running Windows 10

As far as I know, you can't. Windows 10 IoT is meant to be run headless and doesn't include most of the GUI stuff, and even if it did, you'd have to recompile for ARM. Stick with Raspbian.

How to use Raspberry Pi 2 as a desktop PC running Windows 10

As far as I know, you can't. Windows 10 IoT is meant to be run headless and doesn't include most of the GUI stuff, and even if it did, you'd have to recompile for ARM. Stick with Raspbian.