Howdy,
Here you can download the best ps1 emulator known to me.
-http://psxemulator.gazaxian.com/
I figure you should just download the latest version for you'r operating system,
as for installations: i havent tried it yet tbh, it should work fine but if you encounter any trouble be sure to post it here so we can help each other out.
And the roms (games) i dno i guess you should just google it. share it with the other members etc.
you should also be able to play CD's with it.
Good luck and have fun.