As far as permafrost, you generally don’t want to build any sort of house on permafrost unless it is on jacks. Even houses without basements built on permafrost settle and the house will a wreck in a couple of years.
A house will melt the permafrost under it, the water will drain away, and the soil will settle, and your house will eventually disappear into a giant sinkhole. Not a good plan.
I know of a local executive who has made some excavation renovations to his home due to being in a historic district. He was unable to add-on due to the city regs for historic homes, the money difference was not a big deal and since the home is on a hill, he had plenty of room. As I recall the rooms were a wine cellar, a theater, a laundry room, a network/security system room, a bathroom, and a large area around the spiral staircase. All these renovations free’d up space on the upper floors.