"Secondary Panel with specified loads and inter tie with primary service. A generator plug for portable generator. Additional $500 if requested."
Sounds like they specify loads and those loads go into a seperate panel. That panel would have a main/gen breaker with and interlock kit. Install a gen inlet box on the outside of the house, done. Easy money and $500 would cover it in new const. I don't know why they would spec an addtional panel for this. It isn't necessary unless this is a huge house where more than one panel would be installed anyway.
$60.00 for the interlock kit. $75.00 ish for the inlet box, some 10/3 and an extra half an hour of labor is all you need.
I use the interlock kits linked in another post ONLY for older panels. All the manufacturers make them for current panels. I usually use Siemens for new work. They have a kit for about sixty bucks.
I seem to be the portable generator guru in this area. After last years ice storm people are scared that histpry will repeat itself. I am doing an avaerage of one portable setup daily. I'm heading out to do one this am and then to go look at three more. These are generally a 2 hour job that I can fit in at the begining or end of the day.