If you're looking to be a COMPANY driver, I have bad news for you. I don't think there are any company expedited drivers. We're all O/O independent contractors out here. As Ragman says, it's a whole different game.
First thing you have to do before you do anything else is: Burn your "employee mindset" at the stake. If the fire department shows up, give them marshmallows and some long sticks. You're not an employee anymore, you're in business for yourself and from now on that's the way you have to think. Your truck/van/Sprinter/whatever is your business.
Expect a lot of sitting. That seems to trip up a lot of company men, they come into expediting expecting the same thing they had a company drivers where you work a certain number of hours every day. The over 10K GVWR crowd still have to watch their hours, BUT--- nobody guarantees you'll get work every day. You might sit for a few days, then have to weigh the cost of a deadhead move to a better area against the cost of just waiting it out where you're at. Sometimes it's a no-brainer, certain locations have a reputation for no freight so you move, other places are considered hot, so you wait. Sometimes you flip a coin and take your chances.
You're in business for yourself, so all the expenses of your vehicle are yours. Fuel, maintenance, tolls, so on and so on-- all yours. Consider that while deciding which runs you can do and which you'll take a pass on. A run that has a lot of deadhead and goes to a place where freight doesn't happen can be a losing proposition, the only reason for taking that is if you have family in the place you're going to. A run that goes to a relatively good area could be good even if the rate on that particular run isn't great-- it's going to a good area so you might decide to take it.
Living arrangements: You'll have to get used to sleeping in a relatively small place. The sleepers on the big straights and T/Ts offer a bit more room than a CV does, but none of these are going to be "just like home". It's small. It's maybe a bit cramped. You have to be self-sufficient as far as power goes, and you'll need power for air conditioning during the summer, heat during the winter and some form of entertainment while you're waiting for the next run.
About that power: Turtle is our resident expert here on batteries, you can do yourself a great favor by getting as much information as you can from him about setting up house batteries, isolators, inverters and so on. Setting up a generator can be done too, and for some things I would hazard a guess that the genset is the better option. Both will require care though, so don't be afraid to ask the experts.
Don't let us scare you away from this. It's a great life if you don't weaken.