Hey
Then you have 2 separate questions...
1/ for the reflection, I'd use a light wrap technique, which is what should happen here anyway.
To write it the shorter I can, use ChannelBooleans nodes : pipe the
matte of your computer in one input, and an strongly blurred version of the
same matte as a second (FG) input > then choose Xor (or Exclusive Or) as the operation mode of the channelBooleans node... Moving the amount of blur of the blur node now shows you what the Xor does...
Now, you should normally restrict* the reflection to the inner parts of the monitor to exclude the screen but you don't really care as your replacement will be add on top.
(*to do it anyway, you then add a 3d channelbooleans node with multiply as its mode > pipe the original matte as BG again and the last channelbooleans output (of what you've done before) as the FG matte. Now you see where the reflection will be applied, tweak the blur for finesse...)
Now take the replacement screen of the monitor > add an extreme blur node to it > pipe it in a MatteControl node BG > pipe the last Channelbooleans node in the FG > mattecontrol mode : combine alpha. Don't forget to tick "post multiply alpha at the bottom of the MatteControl node. Done
To complete the stuff, you want to merge it back on your comp, with something like "Lighten" as the merge node mode, and adjust the blend.
2/ To keep it simple, I'd only use a polygon mask to follow the curved screen, with a tiny bit of blur, and yes, why not gridwarp or bend(er?) or displace ...