I find I do this quite a lot actually. I don't bother looking at the TV anymore and instead I just play on the screen, like a handheld device.
I'd say it's easier to look at the Wii U rather than the TV as you can easily look at the buttons and actually figure out what you're doing. The TV is more of a second screen so that anyone who wants to watch doesn't have to look over your shoulder and potentially distract you.
Eeh, not really. I like using the TV and I already know the buttons, so it's not that hard for me. The bigger resolution is a plus!
For me it's pretty much the opposite. I have my Wii U connected to my monitor so I just turn off the control pad and focus on the screen. I find the pro controller to be much more comfortable in my hands anyways. There are certain games that really benefit from the Wii U pad though such as Splattoon and doing air strikes by tapping on the map. Overall though, I try to use my Wii U pad as little as possible since it's vital to the system and it's fairly difficult to repair.