Well, not sure if it matters, but removing the HUD from AoD is really simple, just delete the SBARINFO file. To be honest, I thought loading RO after would just overwrite it anyway. I guess I could be a lot more helpful if I would just download this mod and see for myself but nah.
As far as AoD replacing all the items, again, that shouldn't matter since RO is overwriting it with it's own items. Only one thing can replace an item, so load order matters. i'm sure there are scripts out the ass in this, so this is where my logic could be way off.
As far as editing the monster drops - that's easy, but very time consuming. DropItem will be a line in the properties of the monster, but if you're unlucky it'll be A_DropItem in the death state (or something similar).
Oh, in case you don't have it yet, get Slade. Makes editing mods much easier. Good luck to ya.