I have a 2 N5Ks connected to a pair of UCS FIs. The 5Ks are running vPC to the FI
See the attached for the best practice for vPCs. Taken from the vPC Best Practicies guide (supplied to me by Reza). It is for N7Ks but as far as i am aware the same principles apply.
spanning-tree port type edge should apply to all access/trunk ports on the FEX.
Basically, any port that connects to end devices should have it.