Upgrade GW2012 to GW2014R2 in a clustered environment


there is a GW2012 with two PO in a clustered environment. There are tree GW-
Resources, each with a own Pool-Ressource (GWIA, PO1 and PO2). The DVAs are
running on all Nodes.

Where are the caveats in this upgrade? I have seen a short video which seems
that the upgrade is not a big thing, but i like to ask before I do the task.

I think I can do the upgrade off the software on a node which has no GW-
Ressource loaded? The Software is installed to /opt/novell/... and this is
local to the node. But whats's with the DB? In this case the DB is at the
other node and doesn't realize that GW is upgraded.
Whats with the GW Management Web-Apps? Can I use them at Node 1 during the
ressources are running on Node 2?

and so on...