With regards to c2 working on the iPad, according to the min. specs to run C2, An iPad wouldn't have any problem running the software. I think Ashley and Tom are clever enough people to make a very powerful C2 or C3 :) editor for iOS. There's little competition in that market for game making software, tons of affordable third party apps to compliment making games, and Scirra can make a hug impact there.
If it's money or manpower they need, maybe they can raise money on Kickstarter. If there is a will, there is a way.
You can build file management system into the app and store locally. You can also access iPad's photo gallery, resources saved in other apps or from Online web storage sites like Dropbox. I don't think that would be an issue.
I own a Windows tabletPC and Windows 8.1 is horrid. Microsoft doesn't understand touch screens.
I just looked, and a Bluetooth keyboard for an iPad doesn't cost too much. You can buy one for $12. I paid $30 for mine, but it's also a cover.