Well there aren't really any guidelines for what needs to be included in an album or how the tracks need to be mixed. It's totally up to you and the artists, so if you want it to be solely medleys, then tell people that. If you want no medleys at all, let people know that too.
If you want to see how other people are running their projects, take a look at http://ocremix.org/forums/showthread.php?t=31725, http://ocremix.org/forums/showthread.php?t=30903 and http://ocremix.org/forums/showthread.php?t=35647.
You'll see that the Paper Mario one is broken up into different "chapters" and requires mixes to be orchestral in some way, while the Zelda one requires mixers to mix together at least 2 tracks, and the Mana one leaves it more or less up to the artist.
Honestly, just do whatever you think would suit the game(s) best
Also, if you don't want techno, make sure you tell people that as well (Although you'd be missing out on some great talent, and OCR techno tends to be much higher quality than youtube techno).