The fact is that there is a lot of stress that comes along with a career as a truck driver, and it starts in CDL school, and even before. One of the biggest reasons that new drivers fail is that they cannot handle the pressures of training, or the job itself. The number one rule, as always, is "Don't hit anything."
Most drivers attending private school will be commuting, so will have the comfort of familiar surroundings, as opposed to company-sponsored training.
The learning pace at company-sponsored training will be faster than at private school, but in either scenario they are going to teach you enough to pass the driving test, and that's about it.
In most cases, you will be trained by experienced professionals, and your job is to learn, ask questions when applicable, and trust that they know what they're doing.
There will be a lot of stress to deal with, starting even before school and lasting throughout your truck driving career, so best get used to it.
If you are attending a private school, chances are that you will be commuting from your home, and lodging or meals will be your responsibility.
Company-sponsored programs will usually provide housing and some meal allowances, though probably not 100% of your meals.
Yes, it probably will be. The company-sponsored programs are going to try to push drivers out as quickly as possible. You will still receive proper training, but the private schools may allow for a slower pace, or more one-on-one training than the company programs.
Enough to pass the driving test, and it probably won't feel like enough, but the feeling of not being "ready" comes with the territory of being a new driver.
The schools make money by turning out drivers that can operate commercial vehicles, so you will be prepared to pass the exam, so that you can start learning how to become an actual truck driver.