That's going to vary dramatically agency to agency, community to community and state to state.... as will "what is fair".

Depends on the office size, responsibilities and locations. Markets will differ significantly.

It all depends on many factors. Big office, small office, market size etc

The average salary is meaningless. No one wants an average salary. To get the best, you have to pay like they are the best. Your average depends on your State and region. Use those figures as a starting point and go from there.(BTW, I hate averages. Do you want a doctor that got all C's in medical school to operate on you?

You/they will be paid what you are worth.

I guessing about $7 an hour....until THEY have established their worth.

Depends on responsibilities and office size. Larger offices with more agents means more work. Is s/he licensed - that would affect salary also.

What is the position worth to you?

Try to make is a small salary with huge potential for profit share and or production bonuses.

I have no idea... I'm sure it varies from one brokerage to another and from one market to another.

Sadly to add, it all depends. It will matter the size of the agency, the duties of the manager and hours of the job. Some are salary and some are pay plus commission. 

I have no idea. I never hired an office manager. 

It would probably depend on the office volume. A larger office in Florida is rumored to pay $60,000. 

It depends on many things. 

What's fair? The answer just might be what's negotiated and agreed to.