How big a fire pit should I build?

Question:I am building a retaining wall which will be the back drop of a gas fire pit. I was planning the following:

Inner diameter = 55 inches (140cm) 36" SS fire ring
Outside diameter = 80 inches (200 cm)
Height of pit walls = 20 inches (50 cm)
Walk way around fire pit = 28 to 35 inches (70 to 90cm)
The built in seats will be 18 inches (45cm) deep and the back will be 26 inches (60cm) high.

I am freaking out because I am questioning:

1. Will this be too big?
2. Will we be too far from the fire?
3. Will my propane tank provide enough pressure (65 feet or 20m from the pit.
4. Is it better to have the SS fire ring be the same size as the fire pit.

All you fire pit kings, thanks for your help. Keep in mind that it is a hard built structure, so I will have to live will all the dimensions I go with.

Thanks.

Patrick

Answers:
If you have not done so already, try laying it out with spray paint on the ground for the diameters and walk ways. That should give you a feel for how much room it is going to occupy. Try using a folding chair or two to get an idea of the seating. As far as pressure from propane tank, you will have to check with your propane dealer. Good luck sounds like it is going to be pretty nice set up.