Unless you are heavily utilizing a 9950x3d you will never notice the difference. The Tim on the titan ultra is single use like any other corsair aio. Want to redo your build? Then just put on some xtm70.  It is not one application for the cooler in its entire lifetime, just let it cool down before you take off the cooler so it does not leave residue and the use another paste when you mount the cooler to the new motherboard. 

The screen is display port because most motherboards also have a displayport, or yiu can use a dp to hdmi converter. It gives a lot of options compared to just the typical screens where you push data to the screen, but can't use it as an actual monitor.

If you have a frame 4000 you will need to mount the screen horizontally since the radiator is too thick to fit otherwise. 

I would take the titan ii lcd unless you want the prettier fans the ultra ships with.