upgrading Hyper-V 2008 R2 cluster to 2012 cluster

Got a 2008 R2 Hyper-V cluster with two hosts and an iSCSI SAN

I understand that you can't do an in-place upgrade of an existing 2008 R2 cluster. I've spoken to some of the Microsoft engineers at Tech-Ed a few years ago about how to turn my 2008 R2 cluster into a 2012 cluster and i get the high level steps below:

1

Move all VM's to single host

2

Evict empty host from cluster

3

Rebuild server as a 2012 machine, with Hyper-V

4

Export all VM's, save them on the SAN

5

Connect 2012 machine to SAN

6

Import VM's onto 2012 box

7

Rebuild the other server

8

Connect other server to SAN

9

Create the cluster, along with CSV's and all that
my question basically is about the subtle steps that go into some of those high level steps (i may have missed a step or two as well in there, or some could be in the wrong order)

Do I need to break the cluster shared volumes on the original cluster at all for the first rebuilt host to speak to the SAN?

Do I delete any old original VM files from the 2008 Hyper-V version due to the export/import process?

Are there any tricks in order to have the 2008 R2 and 2012 Hyper-V servers talk to the iSCSI SAN at the same time? (so that both see the files), or do i need to Export EVERYTHING, then break communication to the SAN from the 2008 box, before i can communicate with the SAN on the 2012 box?

Just trying to make sure i have the subtle detailed steps in mind before I go about trying to upgrade the cluster. It's possible i may buy a 3rd host during the upgrade process, so that i could create a hyper-v 2012 cluster before i wipe and rebuild the other server into 2012 and then add that machine to the cluster. i just don't want to lose the VM's.