As probably the only person who listens to every airport commision meeting that isn't required to for thier job, I thought I would answer what I can.

I am pretty sure this is referring to the work they are starting to prep for the new terminal. It is work that needs done regardless if they build a new terminal or not. There is a lot of old infrastucture that needs to be replaced.

All the airlines have to agree to any updates as the airline are the ones who pay for it through fees. The gist I get is that Southwest being the biggest usually kind of represents all the airlines since they have the most skin in the game and will pay the biggest share. They agreed to pay for these initial projects. The airlines (again southwest is kind of running it from the airline side and hired their own consultants) also will be the ones who decide on pricetag on the new terminal because they have to approve it since they will be paying for a big chunk of it through fees.

Southwest seperately agreed to pay for a new baggage claim. 60ish million. This part they did on their own they are paying all of it themselves. This is even though the baggage claim life span is going to be less than a decade due to the new terminal. So that tells me they have some expansion plans if they are willing to do that.
The latest public plans are here. https://www.stlouis-mo.gov/governmen...mbined%205.pdf

D concourse and end of C is going to reopen towards the end of next year. It will be needed to move airlines out of A for when they demolish that concourse to start the build of the new terminal. You will be able to go thru security in T1 and get to the Southwest gates once it opens. I wouldn't be surprised to see Southwest take the next bank of gates 3 or 4 (it wont be 6, after those 3 or 4 the next gates are a ways down and they already are stretched out pretty far). They had planned to take 3 more and construction had started but covid kiled that at the time.

The new terminal will be one long 2 sided terminal, kind of like DTW mcnamara terminal.
https://www.flystl.com/uploads/documents/airport-layout-plan-study-highlights/Gateway-Coalition-Briefing.11.21.23.
pdf

The person complaining about jacking up fees in 2010. Thats what happens when AA pulls all the flights. Airlines have to pay the fees and if you have half the flights, fees are going to double. The airport doesn't have a ton of control over that. More flights fees go down, less flights fees go up. Now that more debt from the runway has come off the books (it will all be gone by 2032) and flights are up, fees are back under the average. That should help convince airlines to add more. Its kind of a chicken and the egg thing. You can't get more flights with high fees, but you can't lower fees without more flights.

As to MCI vs STL. STL has about 33% more flights than MCI on Southwest. MCI tops out around 80 a day and STL is around 130. I would think that gives STL an edge for a base but I don't have much insight into it.

There are also a bunch of new resturants getting changed but I doubt anyone on here cares too much about that so I won't get into those.