when does 1031 exchange make sense?

[Namal Burman]

Couple of question i have regarding 1031 exchange? Hope someone expert in Real Estate can guide me

1)Who act like qualified intermediary? is it a real estate agent or escrow company?

2)What is the cost for qualified intermediary?

3)When should you consider 1031 exchange?

I have two real estate property as rental, 3rd one is my primary all based in San Diego. The first rental is a condo which i have been renting it out from year 2013. I have equity on it and yearly i get around $10000 as rental income but the property is 1989 build and i am assuming that since its very old property the equity gain would be limited. So to save 15% capital gain minus qualified intermediary cost does it make sense to do 1031 exchange in selling the old one and do 1031 exchange?

How should i think about it? 

Regards,

namal