Answers

A gutter installer.  Some times a siding installer will, but usually it's a separate trade.

Gutters are installed by specialized gutter contractors. They will make the gutters to fit your home with the least amount of seams.

SIDING CONTRACTOR

Who is the builder sub-contracting the work to? THere are companies that do nothing but gutters. THere are also siding companies who handle the gutters. 

What they said! Typically gutter installtion is its own trade.

This would typically be work done by your Roofing Contractor.

Brenda, Usually a roofing company or just a gutter company can do gutter work. Elbert Construction does it. CAll if you'd like to set up an appointment.

Keli

Usually the Roofing company will do both. I started my roofing company in 1989 and the first 2 year's i would do both. And now it just makes to much business sence to use a subcontractor . But i 90% of my work is existing homeowners if you are buying from a builder They may use 2 different company's very likely if it is a big builder. They are trying to keep there margins as high as they can. A new small builder will normally use one company Usually the Roofing Company. But when i used a sub i was the company that carried the warranty on the roof and gutters. My customers never new they where subs. I hope that helped you. Things are changing very fast in the industry but still do it this way my customers like to use one contractor.