The installs at any given theater are going to vary widely. MF probably has a contract with a film studio, maybe Sony, Paramount etc to install standee's, window and door clings, hang banners etc.
I installed standee's and other promos for a company that had a contract with Disney. We also did audits at various theater chains to report what Disney materials were being displayed and where (lobby, hallway)
Most theaters that I dealt with had their own employee's do most of the work including the simple standee's.
Be very careful of a flat rate payment for standee installs as I will almost guarantee you will come out on the short end of the deal 8 out of 10 times. We had Disney standee's that said in the paperwork would take 2 hours end up taking 6 hours, Luckily the company I worked for (mosiac.com) paid by the hour and not by the job.