1) How long have you been playing?
I joined early 2015

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

3) Do you find healing too boring, too hectic, or just right?
It's all three of those depending on the situation, and healer is a situational role.

4) Based off question 3, which content are you referring to.
All of it. From one shotting mobs 70 levels below you, all the way to getting one-shotted multiple times yourself in Savage/Ultimate. Several things go into how much a healer kit opens up, and the tier of content difficulty is only one of them.

5) How many healers have you maxed and which is your preferred to play? Which is your least preferred?
All my healers are maxed. The healer I prefer depends on the encounter. A simple run down would be: High end (SCH), Dungeons (WHM), Roulettes (AST). It is a notable mention that my SCH is currently on strike.