It would probably be easiest to use WinHIIP on your PC to format the PS2 drive and copy the ISO files. You can then install OPL on your FMCB card and configure it. In my opinion, this configuration works perfectly for your hardware.
Friends said that you can hear your music in the game, but it all depends on the game and its features. Usually some games have this option to turn off the music and play your own. So you just need to go to settings and try to set it up.