Welcome aboard. The team can always use another good member. Now for the reality check. Swift will train you to get a CDL, that's all they're required to do. Talk to your instructors and any drivers you can while at the school. Gather as much information as possible from experienced drivers.
After you graduate from the school and have a CDL in you wallet you will be assigned a mentor. This is the 6 week period in which you will learn how to be a truck driver. A good mentor will make your career and a bad one will break it. You are not stuck with your mentor! If you don't get along or the mentor is bad (making obvious mistakes) then you need to contact your driver manager and get on with another mentor. Learn as much as possible with your mentor, this is the best chance to get "free" training. His job will be to make you the best driver he possibly can, your job will be to not disappoint. Once you're on your own with your own truck your first 6 months driving record will also be reflected on your mentors. If he wants to "cut corners" you need to remind him that you're learning from his example and it's how you will drive in the future. Get as much practice backing as you can, actually do the required pre-trip inspections and perform the minor driver maintenance as needed. Don't just talk about it, actually pull out the dipstick and look at the oil level, use the tire guage and mallet. Check the lights and learn how easy it is to replace a burned out light.
Once you're out on your own be ready to work and work hard. After all they're paying you to move the goods. The notion that you'll get drive all around the country and basically be on a long vacation and get paid for it is bunk. Military recruiters say the same thing, "Join and see the world". In reality you're on the job at work. You will get to see a lot of stuff but your primary responsibility is for the truck and the cargo you're hauling. SWIFT will keep you busy as long as you're willing to work and you'll be paid for your labor.
You'll get out only what you're willing to put into it. Communication is the key here, keep your driver manager up to date, get along with him or her and be nice to the customers. A good DM will make your life very pleasant. If you don't mesh with your DM then get another one. Every terminal has several Driver Managers to choose from. If you don't get along any of them then perhaps a look in the mirror is in order.
Swift is fine company to work for if you really want to work. If you're not really into working all that hard then Swift will allow for that too, your freight will suck, be infrequent and you wont make a whole lot of money. It's all up to you.