Once you get used to it, it's like a pickup truck, but bigger, longer, with a worse turning radius. And don't forget that rear overhang. Easy to take out a streetlight or traffic sign with it.
Do not let anyone linger in the 15-second space ahead of you. You have more mirrors, but they do not eliminate blind spots completely. If the idiots cut you off (as they are apt to do because they are stupid and don't know any better), back off to increase distance. You need maybe ten times any vehicle's length to stop (possibly more in some cases) and you need to be more mindful of mirrors and blind spots when turning.
60 mph? If you're lucky.
70 mph? You're either risking mechanical damage or you got a unicorn.
55 mph zone - run 50.
65 mph zone - run 58-60 if you can.
Always drive slower than the speed of traffic with these things... It's a lot easier to stop when you leave enough room, and these beasts need a lot more than you're used to.
You might check out the links in my sig and get a copy of the commercial driver's manual for your state to help you to prepare for the experience. If you're in Virginia (and don't smoke or vape - I have ridiculous asthma) I can give some pointers in-person.