There are two different groups referred to as 'they': These were the technicians. In theory they [technicians] would have followed identical routines if the President had been named Bert Lahr. In practice, as several of them were to discover that day, their loyalty to the man in Suite 850 had become surprisingly personal, and could not be transferred to anyone else. Officially, however, they [technicians] owed their allegiance to an institution, the office of the Presidency. The politicians, with whom they [technicians] coexisted, were a different breed. Political fealty was completely individual. As a group they [*politicians] were more colorful, more convivial, and less efficient than the technical staff. On principle they [politicians] distrusted clockwork procedure, but they [politicians], too, were obliged to operate on tight schedules, and the baying from the parking lot gave them a special incentive. They had to rouse themselves and find out what was happening, and once they [politicians] saw all those voters yesterday's exhaustion was forgotten; they [politicians] were ready to go. The subject passes from the technicians to the politicians when it says 'The politicians...were a different breed'. Of course, the politicians are bothered by the baying from the parking lot because they are elected, so they need to worry about the voters. Clockwork procedure just means a strict routine or way of doing things.

A turnpike is a kind of road that you pay to use, like a modern toll road. I think they're named after the kind of gate they used to stop people getting onto them for free. The money paid went to the upkeep of the road, meaning they were of a better quality than older roads that had developed over time.

"Drop dead, will you?" I would never use. It's probably equal to telling someone to shut up or go away, but it depends on the context and I suppose it could be said in a joking way. "Drop in sometimes" is an informal way of saying visit occasionally. So if you went on holiday, you might ask your neighbour to drop in sometimes to feed the cat. Or you might say to a friend that they could drop in any time they liked for a cup of tea.

Youtube! There are quite a few films on there broken up into chunks, or you can just watch video blogs etc to get used to normal people talking.

Because it's fun! I want to travel a lot when I can, and travelling is a lot better when you can communicate with people.

People also say "I gotta go" very informally as an abbreviation of "I've got to go."

If you mean 'hot' and 'hotty' then yes, although I wouldn't say it expressed tenderness... A hut is a small house.