Transformation says:
You lose your spellcasting ability, including your ability to use spell activation or spell completion magic items, just as if the spells were no longer on your class list.
Am I correct in assuming that I'd still be able to activate spell-storing (not spell-trigger) items in the same way that, say, a barbarian could, as if it's not on my class list?
Secondly, what about Use Magic Device? Could I UMD a CLW wand? Does that line mean "you can't do this because they're not on your spells list" or does it mean "you can't do this AND they're not on your spells list"?
Lastly, pretty sure I'd lose Arcane Strike for the duration, since it has the prerequisite "ability to cast arcane spells." Correct?
Yes and you could use UMD to activate items still. As to arcane strike would probably be disabled while transformation was active (I would say I'm about 80% on this one).
I think i'd rule the other way on Arcane Strike. It's of limited effect (though stronger than say weapon focus) and to disable it is basically a feat tax. While transformed you are remarkably better at melee true and you trade spellcasting for that, but being transformed does not eleminate the stored magic potential that fuels AS.
Just my take.
Thanks, folks!