Multiple iOS devices in the house...multiple AppleIDs?

My wife and I are about to get a second iPad so we each have our own. Up to now, we've had all our iOS devices (her phone, my phone, and the family iPad) all one one AppleID, which is handy because it allows us to have the apps we want on each device with just one purchase.

However, going forward we're going to want to do multiplayer gaming, and particularly asynchronous multiplayer gaming, using our iPads. (Up to now the only multiplayer iOS gaming we've done is pass-and-play stuff, because we mostly game on the iPad and only have one anyway.) So my question is twofold:

1) Is there any way to set up multiplayer games using a single AppleID? In other words, can I start a game of Uniwar with me as player 1 on my device, and her as player 2 on her device, but all on my AppleID? I assume the answer to this question is "No, don't be stupid."

2) Is there any way for us to share apps without buying them twice? Most of my apps are just for me, but we have lots of games that both of us use, and a fair number of apps we bought for our toddler that it would be good to have on both devices. If the copy of Uniwar on her device is "owned" by my apple ID, could she still play a multiplayer game under a different ID? That's really the key question: can I have her iPad have "my" apps on it while still letting her log into them as herself?

Apple likes money, so I would assume all the answers to your questions are "no" :)

I've got two ipads on my account, one is at a friends house. Thought it would be fun to imessage or facetime her, which I don't think is possible with one apple ID.

So, meh

I can tell Ben thinks I am dumb for even asking this. Apparently it all works fine. So never mind.

Both Facetime and iMessage connect based on the email address associated with the device, not with the Apple ID. If both devices are linked to the same email address, then no, you can't Facetime between them, or use iMessage to send texts between them. If you tie one of them to a different email, though (which you can do in iPad settings... er, somewhere. You'll have to look for it), it works fine.

There is really very little reason to use multiple Apple accounts in one household. Apple even recommends sharing an account.

What Ben said.
We have two iPads and three iPhones in our household with three primary users (the iPhones) - all five uses my Apple account but have their own separate Apple ID's (just for iCloud having three separate ID's mean free backup - if we only had the one I'd have to buy more space). Works perfectly.

We do something similar. We use the same Account for iTunes and the App Store but each device otherwise uses its own AppleID

I do the same too across two ipads. one Account (mine) across both for the app store, all the apps can get shared. Then each has its own account for iCloud / backup.

I think you could play against each other, just sign in to gamecentre with different apple ids

Yes, this is how it works now. They used to let you just make a new Gamecenter account (that's how we handled it when we first got our iPad), but now they have changed it so that multiple users sharing the same account can each have their own Apple ID. Which is probably a better way to do it, since it addresses the problem of account sharers also having to share a single iCloud drive. You can set it up right from within Gamecenter, it looks like. Go to the "Me" tab, sign out the current account, and there will be an option to "Make a new Apple ID."