Cisco Switching/Routing :: Nexus 5ks Connected To 6513s - Peer Link Active?

how the Nexus 5500s work ?currently we have two 6513 Core switches  6513-1 and 6513-2 running HSRP and RSTP.  6513-1 is currently the Root Bridge, 6513-2 is setup as our secondary root.  We also have two 5548UPs setup with a peerlink between them.    Picture attached. "Current Setup.jpg"
 
There is a 20gig port channel between the 6513s and also a 20gig port channel(peer link) between the 5548s. 5548-1 has a 10g fiber running back to 6513-1 and 5548-2 has a 10g fiber running back to 6513-2.  Currently now Spanning tree is blocking the link from 6513-2 going to 5548-2 which is what we expect.  We were working on moving some things to different racks the other day and moved switch 5548-2 to another rack and brought it back online without the peerlink fiber connected. We started to have issues and tried to plug the peer link back up, but still continued to have issues.  We started to troubleshoot and noticed that both 5548s were acting like the master of the VPC domain and was not letting traffic pass accross the Peer Link.  We then rebooted the 5548-2 with the thought that it would come back up as the secondary in the VPC domain.  When it finally finished booting back up it then caused a huge loop in our network accross both uplinks to the 6513s and the 5548s peer link which in turn took our network down.  Spanning tree did not work like it was suppose to and block the port going from 6513-2 to 5548-2 in time.
 
My thought was this didn't seem like a good setup.  I went to the drawing board and decided we needed to have an uplink from both 5548-1 and 5548-2 going to 6513-1 setup as a port channel/VPC and also a uplink from 5548-1 and 5548-2 going to 6513-2 setup as a port channel/VPC.  Picture Attached. "NewSetup.jpg"  We are also planning on buying a "2K-C2224TP-1GE" to hang off the 5548s to use for ethernet.
 
how the Nexus 5ks work and haven't done a lot of research on them. Would this not be a better setup since both switches will have an active link to the root bridge?  The links from the 5548s going to 6513-2 should always be in a block state until we loose both uplinks to 6513-1 or the entire switch itself correct?  Also how will the 5548s reactive if I was to loose the Peer link fiber?  Will they continue to work as normal?  When it looses this Peer Link does it suspend all the VPCs for the servers on the secondary switch in the Domain so the network doesn't get confused on which link to send traffic up since there isn't a peer link active or is this not the case?  Also with the peer link down will the 6513-1 know which 5548 to send the traffic to if there is only 1 device (not setup in a VPC) on one of the 5548s?  What are your recommendations/best practice on the setup for the 2k?