1) How long have you been playing?
I started with the open beta but stopped for a number of years - I've had spurts of playing here and there so it's hard to tally it all up.

2) Do you use controller or mouse/keyboard?
Mouse/keyboard

3) Do you find healing too boring, too hectic, or just right?
Just right!

4) Based off question 3, which content are you referring to.
All of it, at the moment. I'm still working through ARR and dusting the rust off my playstyle so I'm still learning a lot. I stopped playing shortly before Heavensward came out IIRC and I've either forgotten a lot of my strats or so much has changed that the strats I do remember aren't viable anymore.

5) How many healers have you maxed and which is your preferred to play? Which is your least preferred?
None yet, but I'm putting most of my time and effort into WHM