Brokers have a lot more experience, often have companies that specialize in mortgages, and they have direct connections with appraisal companies.  

I am very interested in working with investors seeking vacation properties, long term rentals, boutique hotels, multi-family rentals, and more.

I have a friend that is a CPA that I have been asking tax questions to and although she has been helpful so doesn't specialize in Real Estate taxes.Thanks for bringing this up!

@John Burtleyou will find different banks have different rules and different things they specialize in.

I have over a decade of experience specializing in SFR (buyers, sellers, first-time homebuyers). 

I am looking for a broker I can pay a fixed monthly fee and pay no transaction fees/splits... so that If I buy or sell a rental portfolio I do not have to pay huge amount of transaction fees.I am also looking for a broker that understands the investment business and is comfortable with with special transactions (subject to, assignments etc. etc.).Any suggestions?

You might consider Niche or Specialized Housing like student housing.

However, I see a tremendous opportunity to become "the guy" who specializes in supporting a fantastic hard working / family oriented culture. 

Sure, every broker/realtor has to differentiate themselves somehow, but claiming to have a unique, special, or "first" access to properties isn't accurate.  

I also have an agent on my team that specializes in and around the Center City Philadelphia region and surrounding.