Hi Will,
Welcome to the BP Forum. I'm a real estate investor with an active real estate sales associate license and a general contractor license in FL.
Licensing laws are state specific so I can only provide insights to you based on Florida licensing laws. Illinois could be different or similar but please verify.
1. In FL, to get a real estate sales associate license, we sign up for a 64 hr pre-req class, passing the class will allow you to take the state exam, passing the state exam we will get our sales associate license, which most of the real estate agents are. Sales associates only allowed to work under an active real estate brokerage (RE/MAX, Keller Williams, Century 21, etc for your big name brand or you can go with the local boutique mom and pop office). In FL and I believe in many states, you need to maintain the sales license for 2 years (or 3 years in some other states) in order to be eligible to take the broker's exam and obtain the broker's license. When you obtain your broker's license, you can either a.) start your own brokerage, with that you can choose to grow your business and recruit more sales agents to work for you, or be a solo-agent broker, or something in between. or b.) decide to continue working under another brokerage, essentially staying as a salesperson but with a broker's license, which term: Broker Associate. And in FL, a real estate license will let you earn a commission on any real estate related transactions: residential, commercial, business only with no real estate properties, property management, real estate consulting, etc.
In summary, if you were in FL, a broker wears the business owner's hat, there is no way to become a broker without having at minimum 2 years experience under your belt. And if you want to do sales and make big money on your own, stay as the sales associate is the way to go.
2. You can be a part time agent, but don't expect to be a successful one. Everyone I know in this industry fall in the two category:
a.) Not making enough money as a real estate agent and decided to not keep their license active at the licensing renewal time and go back to their primary job.
b.) Making too much money, way more than their primary job and they decided to go full time and quit their old job.
I have never seen a successful real estate agent doing this for more than 5 years as a side hustle.
3. To find a good broker, first you need to decide what do you want to do. Do not focus on the commission split. Training and mentorship is much more important than a few percentage in the long run. If you like to keep things flexible and low cost just to feel things out, then go with a virtual broker office with 100% commission on the agent side and they don't have any commitment required for sales agent. If you would like to make lots of money ($300k to $500k a year or even more in very expensive areas) and be a very successful real estate agent, then you gotta hustle and look for the broker that runs a successful sales team. I also see lots of mediocre agents just makes ends meet and half *** in their job and just survive. The good ones maybe breaks 6 figure in commission but average agents make about $40 to $80k a year.
Hope this helps answering some of your questions. If you want to talk more, feel free to dm me. Personally I fall in the category of a real estate investor with a real estate sales agent license. I'm not a mega bucks top producer but I've been with REMAX and small boutique brokerage. Everything I said it's from my perspective either personal experience or conversations I have with lots of real estate colleagues.