Would one need multitrack or multi weapon fighting to reduce the penalties when full attacking with all four arms making unarmed strikes?
Multiweapon fighting shoud work normally if your GM allows you to pick a bestiary feat.
Multiattack won't work since it's for natural attacks only. A monk doesn't make natural attacks, but "armed" unarmed strikes.
Finally, as Vhok says, the flurry column table states how many attacks you make when you declare you flurry. Having more arms does not grant extra attacks while flurrying.