Wife About to Get Real Estate Agent License - Tips

Hi all, 

So my wife has been a stay at home mom for the past 7 years. She's about to take the test to be a real estate agent in South Carolina. I have a good and steady day job (plus side gigs) along with one rental (past 5 years). We're interested in expanding to perhaps up to 4 or 5 rentals and perhaps do a flip here and there. We're pretty conservative people, and I'll get into more specific questions down the road about how we might achieve those goals.....but our immediate question(s) is: what to look for in an investor friendly broker to hang her license with? She'll be doing the standard buy and sell for clients (another question: is the split between broker and agent negotiable?) Doesn't seem so at one firm thus far....Third question: has anyone negotiated a different split with their broker for personal investments? So what say you fine folks. General tips about the above and of course anything else you'd like to share in general about getting started both in the standard buy and sell agent role and the investor role. She plans to read the blog post about Working with Investors as a Realtor along with Keller's Millionaire Real Estate Agent book. Thanks!