Hi Ann ...building a house on pier and beam should not require any specialized builder.... its  a very simple process where work is really during design (civil/architect) and design work should not have  any additional cost as well ...

Anyone have a contractor they have worked with in the past to remove a load bearing wall and put in a beam?

Yes, rent rate per sq foot, but you also have to offset that with extra hallway space which doesn't make money, premium pricing for first floor or near elevator, Large sizes closer to elevator and smaller sizes away, larger sizes on first floor and smaller sizes higher up, ADA compliant hallway/door width/elevator sizes, cart sizes, cart corner bumpers, foyer area, any box/product sales (sqft taken), placement of elevator in the building to minimize distances, structural wall and beam placements,  etc. 

Hello BP friends, I've been extremely laser focused in on trying to get into real estate investing this year and have a goal to buy a good cash flowing deal before the end of the year. 

The finished product will be new 6,500 sf. open span space with steel beams and everything.

And on the second floor there's a very noticeable bump in the flooring where I assume a beam to run.

So you might want to read on these articles/threads:How to Effectively Conduct Joint Venture Agreements as a Real Estate Investor596231-how-do-i-properly-construct-a-purchase-with-a-partnership591376-create-an-llc-for-first-partnership-best-way-to-do-so526244-taking-on-partner-s-and-limiting-our-liabilitesSecond, @Dustin Beam and @Thomas S. and are correct in the strict sense of your question - no tax advantage.

If you have a laser level, that will be better.If there is significant sloping, you might need to repair the foundation.

My crew actually loves working on them because given they roll out of a factory type build, they tend to be laser straight and without the oddities we find in some older stick built homes.   

Let their experiences save you time and money to stay laser focused on your own goals.