So I think you've pretty well nailed down the fact that you need more multiples of the smaller cards to really make these decks go - namely the commons/uncommons that you have 2-4 of to ensure consistency when you play.
For the B/G, you clearly have a few good cards that have some value (Gravecrawler, Liliana of the Dark Realms, etc), but to be honest, getting a B/G zombie deck to work properly and be competitive outside of the kitchen table is an expensive proposition. To that end, I would actually advise going with the R/W setup and using those two cards from the B/G deck as trade pieces to secure a few more pieces for the R/W deck.
Now for the R/W deck, again, the first real problem for you is consistency and the second is direction. You should have a clear direction that leads up to your primary and secondary win conditions. Thus, you need to ask yourself, how do you envision yourself winning the majority of your games with this deck? Are you going to overrun them? How about aggro like crazy? What are your counter strategies? How do you deal with a Geist of Saint Traft or Thragtusk? Or perhaps the better question, can you deal with them?
Given the cards you have, you actually appear to have a variety of win-cons, but none of them is really focused in on very clearly - and many of them can be achieved with only a few things being switched around. For instance, Hellrider and Fling can prove to be hilarious/devastating pieces, but only when utilized properly. What were you planning on using Fling on?
Personally, I would invest a bit more on another Dual Casting or two and then toss in Cathars' Crusade and Thatcher Revolt. Make the Crusade the absolute top of your mana curve and then try to secure a few Intangible Virtues. Then you're going to run crazy R/W token aggro. The idea here is that you can drop tokens from Krenko's Command, Krenko, Thatcher Revolt, Gather the Townsfolk, Midnight Haunting and the like. Intangible Virtue (and to a lesser degree Phantom General) pumps the tokens. You have a variety to avoid Detention Sphere and even in the case where you get bogged down, the Crusade will pump them all to be huge - or in another type of pinch, Hellrider lets you attack for fatal damage without ever even hitting them. Then I would focus much more on removal (Oblivion Ring, Pacifism, Searing Spear, Pillar of Flame, Mizzium Mortars, Annihilating Fire, etc all come to mind). You can even include a variety of white combat tricks like Rootborn Defenses and even some other fun ones like Trumpet Blast and Dynacharge that could be copied with dual casting to offer huge bonuses on otherwise insignificant attacks.
Lastly, I would suggest going R/W simply because you have more time before that pairing becomes the standard fare (Feb 1 is the official release date for Gatecrash and Boros). Thus, you might still be able to swing some of the Duals and whatnot for more workable value.
Anyway, mull all this whatnot I've said above over, but keep in mind that you could likely turn this into a pretty competitive deck for somewhere in the $20 range, or just a few well placed trades.
Good luck!