Hi, my wife and I just bought a 64GB wifi + 3G iPad that we'll be sharing.

Two questions straight out of the box:

1) We'd like to put purchased content or apps that each of us has bought with separate credit cards onto the iPad. Is this possible? Or can an iPad be associated with only one iTunes account which in turn is linked to only one payment method?

2) We were going to get wifi only, but got 3G because the wifi-only was out of stock and we thought we might give 3G a try. The guy in the Apple Store said most people in our area buy AT&T rather than Verizon -- apparently with the AT&T version you can put in a SIM card and use another 3G provider? We're going to be going to Europe in a couple of weeks. Any suggestions on the cheapest 3G plan around that would give us coverage in Europe? (We'll only be there for three weeks, so we don't want to lock into something if it means paying for something we wouldn't use later.)

1: yes.
2: don't know.

Two accounts is possible, but can be a pain, especially with updates, any reason you cant just use one account?

Don't think there is a good Europe wide sim deal, the roaming rates can be terrible , you'll probably better off buying a local sim for each country you visit.

Agreed it is a pain, but it works. My wife has all my apps on her iPad and I update them once every few weeks.

As for the travel plans, I'd pick up a SIM cutter (under $10 on Amazon) and buy a local data SIM.

If you add the 2 accounts using the computer, and sync devices after, there should be no problem updating on devices, just need password when asked, try to have both devices use one account and only use the other one for updates.

1 account can be used on 5 pc's.

2) AT&T models are factory unlocked and you can put any SIM card in the world. I bought a AT&T model in USA and use it now in Lithuania / EU with a prepaid card. Works just great. You just need to know that iPad2 uses a microSIM card which is smaller. In Lithuania providers have it and it costs 5-6 EUR (I bet it's a bit more expensive in western EU). But you can make your own with a scissors (I did that). Just use a microsim template from the internet or buy a microSIM adapter: $1.09 - Micro Sim Card to Standard Sim Card Adapter (Black) - Gadgets
They come with a sticker which helps you cut correctly.

I have 3 iTunes accounts and several hundred apps, plus music and movies all sync fine Updating apps is not that bad the ideal way is to note down where you purchase what from. iI have 3 iTunes countries all up USA, Australia and UK all sync fine. Hope that helps