Hey Barbara, starting with an FHA loan for your first multi-unit property is a good choice but converting it to a commercial loan later may be challenging.

I'm interested in setting up either an S-CORP or LLC, but want to make sure i make the right choice so that I can secure the best tax benefits, while also setting myself up to get into the next investment. 

The choice depends on your priorities, risk tolerance, and financial goals.

This might entail improving the apartments to support a higher rent or finding methods to increase their worth.Think about if renting out your homes yourself is the most economical choice.

If you plan to sell quickly, a bridge or fix and flip option is probably the right choice.

And that one plat is worth $1,000,000...so the builder's have no choice to build a multi-family property there just to make the numbers work.  

Tulsa  is a good choice overall.

A lot of your choice will come down to some personal preferences, lifestyle and pace choice and, as others mentioned, financing.

We also do not really want to go down the whole personal guarantee, W2, tax return, credit score route... or is this something we will have no choice with without hard money in this climate?

I think you may have very well narrowed down my strategy choices down to one of three; the BRRRR method (although this might be too much to start with for a newbie), the live-in flip that you mentioned (probably the most practical as I've been part of many different projects in the construction industry), and a combination of house-hacking/live-in flip (probably the most rewarding with a potential to swap between units as I finish one in order to bring better rental income).