Hello,

I submitted an app minutes before the deadline and it's still in validation process in the AppUp program, is there any problem with it for the contest?

The FAQ says:

Does the app have to be validated to be considered for judging?
Yes. Since we are looking at the user experience of the app downloaded from the store on the device, our judges download apps directly from the Intel AppUp Center in order to judge applications. For your app to be considered, the application needs to pass validation and be available for our judges to download in the Intel AppUp(SM) Center.

So your app needs to be validated to be considered for the contest. Therefore you always should publish the app early enough that it is validated till the contest deadline.

And, in the submit form of the contest there were 3 options: Netbook (Windows), Tablet or Meego (netbook and tablet). My app is for Meego Netbooks -although the UI is designed to use it with touch screens also, but I hadn't time to test on tablets- and I selected the third option because there wasn't a category for Meego netbooks. Is that ok?

I guess they'll test it on both device types:
if it works on both (although you didn't tested it) it's fine otherwise it fails.

Best regards
Andreas