Try to read the multifunction's code and remove what you want, or pay someone to do the job for you.
with mobs --> you can spawn mobs inside of this zone..
with full buffs --> no comments here.
with respawn after kill --> there's already respawn code.
So, register your zone in file ZoneId.java paste in your eclipse the L2MultiFunctionZone.java file, remove restrictions, reward, whatever you want, and keep only what you need.
It's old, can be done with less lines, but it's good enough for free.
Also, you will need to touch the method updatepvpstatus in L2PcInstance(Player).java
If that Isn't clean for you, send me pm.