I would be focusing on cleaning up bookkeeping, communication portal with client, vendor list management, payment processing, etc. 

Accounting and Bookkeeping: Since we plan to build a diverse portfolio, we want to ensure we’re setting up our accounting systems correctly from the start.

In other words, is this system focused primarily on rent collection, rather than full out bookkeeping? 

Now that I’m growing my portfolio and have 25 units it’s gotten more complicated and he recommended I get a bookkeeper.

As a bookkeeper here is what I tell potential clients. 

Did you have people like a real estate agent, contractors, bookkeepers, a CPA, and all of those other roles already on your "team" or did you just purchase the first property and find people for those roles as you went?

Not sure if you'd like to self-manage or not, but either way you'll need to build out a good team - realtor, property manager, contractor, bookkeeper, etc.

You'll need to get a good investor friendly CPA, possibly an LLC, bookkeeper, umbrella insurance coverage, separate bank account for rental. 

I personally did a double major in accounting and finance and while I do not practice accounting as a CPA or bookkeeper or anything it has helped me tremendously to navigate real estate and understand the tax code or where to find answers to tax questions.  

I need to learn how to leverage equity in my property, how to improve cash flow, how to improve my property, understand book-keeping, create the right structures to limit liability, create the proper structures for tax, and learn how to find deals.