No. Definitely not. The Wii U will not have the same level of functionality is your home computer.
No, what these services do is provide a network to use for such as playing online, friends lists, a place to go with customer service issues, etc. You can buy Steam games on a disc. You can buy Origin games on a disc. If DD is happening, it will not be because of this, this will just be part of it.
We'll have to wait and see. With Portal 2, PS3 and PC users can play together. There are some 360/PC cross-platform titles. It's possible, but it's a matter of if they'll actually do it or not.
I won't speak for Origin but Steam games have DRM that's not at all intrusive. Prices vary greatly for digital content as a whole. WIth Steam, prices are always the same as the disc's MSRP and then get price drops over times. There are sales as well. One thing that Steam is well known for.
On Steam, this is typically independent from Steam (might be different with Valve's first party titles.) You don't run the games in Steam, but rather, Steam is a launcher that then runs over your games. So titles function the same with or without Steam in terms of the files themselves. Steam has a cloud service that lets you backup your games online that is tied to your account. You can also backup your games at any time.
Assuming they use one of these services, it will be a matter of how deeply integrated it is. If Origin or Steam solely becomes the online aspect of the Wii U friend codes will be abolished. Unless Nintendo is REALLY stubborn about friend codes and sticks them in alongside Origin.
Anyways, this is all speculative, but I hope I've brought you up to speed about what we already know about how these services work currently.