Q- I still have MultiBit running, and I am curious what will happen when I send some funds using BreadWallet? Would my MultiBit wallet be/become usable by transferring a small amount of coins?
If both wallets are online and working properly you should see your funds simultaneously move in both wallets when you send them from BreadWallet. I don't know if your multibitHD will become usable by transferring a small amount of coins because I don't know what bug made it unusable.
Q- Do wallet words essentially allow the "syncing" of funds over several wallets using what is essentially a private key (being my wallet words)? Is this a form of redundancy?
Yes, the wallet words are the only thing you need to backup to secure your Bitcoins (unless you used a password combined with your wallet words). You can use them in alternative wallets with compatible wallet word formats for disaster recovery. Bread wallet has a compatible wallet word format to multibitHD, so you can use it to access your multibitHD Bitcoins.
In closing, I would like to test all this by buying HI-TEC99 a pint of beer for your help... could you PM me a receiving address at your convenience?
We aren't allowed to post Bitcoin addresses in threads, but you can find mine in my profile at this link.
https://bitcointalk.org/index.php?action=profile;u=325680