Do you have everything setup as a module or a mix?  That can certainly
change things.  It might make sense to re-build the kernel so that the
MDADM stuff is modules, but the rest is compiled in, or visa versa.

Here is all the information I collected: http://pastebin.com/VF4Sfrq5


Regarding the testing setup, we can safely consider whole system as a
test, we will rebuild the system once we figure final config anyway.
So we can play around with the current raid with no risk of data loss.