Most Likely we would have to buy the property with a loan and get a construction loan for the upgrades to convert.

If a money partner puts up the cash to buy a deal - they're paid back when the deal is sold or refinanced.But you have them being a money partner AND owning the deal (I think).I also wouldn't worry about what anyone else has done.  

Should I be trying to buy a 3 or 4 plex to start or would utilizing a good chunk of equity and looking for a much larger investment like a 15+ unit be better?

(you can't buy it from her but she could have an estate opend and then you buy from the estate) Your next chance is simply watch for notices of sale or auction but that may never happen

I invest in Tampa area and have a LTR  and about to buy a house in next 3 months as primary and then after a year convert to STRAnyone here have a connection who will do  short term JV ?

Depend on your situation, you can probably just buy insurance.

Primary home to live in:When do I want to buy?

I have been in my home for 7 years and have accumulated some equity and wouldn't mind using this to buy a rental 

Probably in the smaller markets like the Midwest.....you can buy partials too

You can buy the package off BP for 100$ if you're just looking to get something.