Well, my game only meets every other week, so there's very little news since I first posted. (And even if I'd had a game session since then, it's likely to take a fair chunk of time in-game before any of the eggs hatch...)
The one new notion that's come up is: trying to place most of the eggs into some form of stasis or suspended animation - which means they'll probably only try to raise one of the things at a time.
And speaking of thread-jacks (which, fyi, I totally don't mind), I'd have to agree that trying to ban one's SO from playing in games one runs is not a good idea. Sure, be aware that there can be issues with impartiality, but you should be fine as long as you're watching for such issues, and - more importantly - have made sure that your players know they can just tell you if they think there's anything wrong. (As a side note here: it is important both to actually be reasonably impartial, and to appear to be impartial. If someone thinks you're showing favoritism when, say, it's actually just the result of really lucky die rolls, things can go downhill just as easily as if there's actually some systemic bias.)
Same goes for GMPCs, really; they're something that can easily go wrong, sure, but as long as you're aware of the pitfalls, and your players know they can say "Hey, this NPC is hogging the spotlight, please don't do that", they can also add a lot to a game. One of my favorite GMPCs was actually from a 4e game I ran for a few sessions - the party didn't have a defender, so I built a minotaur fighter. She had an intelligence penalty, and a wisdom bonus - so she knew she wasn't that smart, and was perfectly happy to accept tactical advice from the PCs. Still, my general rule of thumb for GMPCs is that they should do their best to fade into the background.
(Incidentally, I do know one GM for whom 4e really is the perfect system - because what he actually does is run a freeform game, but likes to have a framework for combat; and as that's really all 4e provides, it works perfectly; gives him mechanics for the stuff he wants mechanics for, and doesn't give him mechanics for the stuff he'd rather run without mechanics.)