Usually people just like to use what is comfortable for them. Putters mainly range from 33'' to 35'' A taller person would use a 35 and a shorter person a 33. If you are tall and buy a 33 you will strain your back if you are constantly practicing.
28"
Yes, you are permitted to use the back of your putter.
It depends what clubs you are comfortable with, and what length of course you are playing on. If it is a long course, driver, 5 iron, wedge and putter. If it is a mid range course, 3 wood, 6 iron, wedge and putter. And if it is a short course, hybrid, 7 iron, wedge and putter.
A belly putter is designed to be anchored into your belly button and then you can use any variation of a putting grip you want. The idea is that the putter pivots about your belly button, and you swing it without as much use as the arms as you would find with a normal putter.
You would usually only use your irons and wedges as well as your putter. But you may need your woods depending on the length of the course.
You would use a putter when you are on the green, or just off the green to roll the ball into the hole (well that's the plan!)
A tape measure.
No, it would not fit.
When taking a drop you can use any club in your bag, a belly putter is perfectly legal.
You don't
NO!
Scotty Cameron