Is there a law that says ex-felons can't work as commercial pilots?

Airlines from the U.S. contract pilots based on their qualifications and the right to work in the U.S. It is ilegal to discriminate against race, ethnic background, veteran status.

The answer is a bit complex. To a degree, what you hear is correct - but it does not quite mean what you might otherwise think it means.

Consider your first job (maybe while in high school), working the drive-thru at McDonalds. It's a honest job, but most folks (especially youngsters) don't intend to do it for the rest of their lives. The expectations are that you will change jobs a number of times (hopefully for better jobs with better pay) before you are finally established in a career. Pilots are in a similar situation.

For many pilot jobs, especially with getting to the airlines, it is all about the hours. Those hours represent both experience (and some hours are better than other - twin engine hours are better than single, and jet is better than piston). But paying for the hours yourself is beyond the reach of most people. So pilots who want a career with the airlines usually have to start at the bottom. They scrape up enough money to get their commercial license and instructor rating, and start instructing - often in a rental plane older than they are, and for so little money that they too are working the drive-thru at McDonalds.

They accumulate enough hours (and contacts) to start helping out with late night freight delivery (called being a freight dog). Maybe get some charter work. Than a full time charter job. Move up from there to a small regional carrier or one of the charter jet companies. Then finally, if they are lucky, to the majors. And yes, this means changing jobs several times.

Now understand, some pilots love instructing and may do that for their entire time. But for most, instructing and hauling freight and the rest are just stepping stones to their "dream job."

Once with a major carrier they typically stay with that carrier if at all possible. Within the carrier, the pay and job quality and other perks are determined to a large degree by seniority. Switch to another carrier and you may lose all that hard earned seniority. [Pilots generally hate mergers and acquisitions, since that may affect their seniority, without them having any choice in the matter.]

So yes, a freshly licensed commercial pilot may indeed change jobs a number of times on the way up - but probably no worse than a lot of other career paths.

Usually, once you have a private pilot certificate you would go for an instructor rating and work as a flight instructor to build flight time (while making money). Along the way you could also be working on your commercial, multi engine, and air transport pilot ratings and certificates. It takes time to get into the airlines, mostly because you need to build flight time and experience. Even when you first break into the airlines the pay is kind of pathetic, but it builds quickly over time.

Not likely. Flight schools get paid for teaching people how to fly. If they paid you for learning how to fly, they would go out of business. If you worked for them you could gain flight hours teaching others to fly, but you need hundreds of hours before you can become a flight instructor.

Many colleges offer flight training. Two that come to mind are UND and University of Cincinnati but there are many others. You might look into that as most airlines want a degree also. Regional airlines pay is garbage but you get raises pretty quickly as your time builds.

Not true. High marks will give you your choice of what you want to fly. So if you want to fly the F-22 make sure you get to the top 1% of your class. Same goes if you want to fly say the KC-135.

Becoming a commercial pilot does not *require* a college degree. And many folks are out there crop dusting, performing aerial photography, even teaching flying - all without a higher degree (and some probably without a high school diploma). However, it is NOT the path I would recommend. The higher up the ranks you climb, the more likely any particular institution (whether airline or other) is to want one - even if it really is not directly related to your flying work. With lots of entry level applications, it is just an easy way to weed out the bottom tiers. This is especially true of the airlines.
Also, do not forget that every commercial pilot flies at the risk of their Class II or Class I (the latter required for ATP "airline" flying) medical. I highly recommend that all pilots have a "backup" life plan for the day when they are no longer able to fly commercially.
There are two traditional routes to flying - military and civilian. The military will pay for you to learn to fly, and it is an excellent opportunity and career. But, you have to be accepted by them - and that means good physical and mental condition. And they are most likely going to want to see that you are on at least a path towards a college degree (ROTC, for example). Of course, they are also going to want a long-term commitment from you as well.
Civilian is usually "pay your own way" - at least for the beginning. You can get a pilot's license by working the drive-thru window at McDonalds (to pay for flight school), but it's a tough way to do it. And merely having a license is not enough - you need lots of hours (preferably in jets) to get hired by the major airlines. So that's a lot of time at low wages and strange times - or pay for more of your own training.
Lastly, some airlines do offer ab initio training (training from the beginning), but that is usually foreign (non-US) airlines offering jobs for their own countrymen. Lots of applicants, for a relatively few slots.
Bottom line: Flying is a wonderful career, but like anything else worthwhile - it takes lots of time and effort. If it is something you want to pursue, then don't be afraid of working long hours at perhaps multiple jobs to earn enough money to start getting your license. And then more hours and strange times at relatively low wages to make it into the airlines.