Looking for a photographer in St Pete FL to get some pics for my furnished medium term rental.

If you're going medium to large multis,which it appears to me you are,I think it's probably tough to limit by geography.And it won't make any difference anyways since you're supposed to plan for PM in all the BP calculators,even if you plan to self-manage.Look in all the top hot markets:Tampa,Jacksonville,Nashville,Austin,Charlotte....Analyze all the deals that look good at first sight much deeper with the BP calculator and decide on a few to make offers on.Try to cold call a commercial agent and ask for off market deals in those markets.By the time deals appear on LoopNet and cityfeet,it's too late.Good Luck.

I will eventually trade up to medium size Multi properties (20 - 50 units).  

I'd also like to know if you are utilizing a property management company that specifically caters to medium term rentals. 

What mediums do you suggest for finding those deals in order to efficiently build my network and portfolio?

I'd suggest you get a good CRM system, start capturing those calls and get them each on a followup program based upon your initial interview (slow, medium or fast).  

As I'm building my buyers list I noticed the the majority of buyers are asking for properties in the same area and those areas are way below the medium.

. $200 initial pet fee and $35/month pet rent is usually more than adequate.Also as a side note on the 25 lb limit some Landlords elect to utilize, I have seen significantly more damage to flooring, walls, and doors from small and medium size dogs over large dogs.

I am looking at a historic property, about 25,000 SF in a CBD in a small/medium east coast city.

Look for the place that did not go through a lot of highs and lows, has jobs, a above medium income from state average, a growth opportunity and  a renters market.