Parnell, I visited Estero this summer! Estero was my base of operations so to speak. Traveled to Sanibel island, and Key Marco. I got a much better appreciation for the environment they lived in. This includes resources. I realize the island vegetative communities have changed some, but it still helped walking the same beaches they stood on. Also visited corkscrew swamp and some other wild places.
I noticed rocks in the water that looked a lot like a loose grit limestone. These looked like good grinding or pecking stones. I began to wonder how they made holes in shell or cut out blanks. Flint? Shells? Was this a striking effort or a grinding job? I am certain they traded for what they wanted. I suspect they may have been in charge of the marine shell trade with inland mound builders that were their contemporary. Getting rocks should not have been a problem. What I don't have a good feel for is if they did trade for stones and if so how much?
Like you I realized there were no clear indications of archery use by the Calusa. Atlalts have been found on Key Marco, but no bows and no arrows. This by no means declares archery didn't occur, just that it is not definitive. I am a native of Missouri so I have no earthly idea what half of those trees were down there, and certainly less knowledge of what might make a decent bow. Your observations are interesting. I have blanks cut for shell Celt and need to layout a shell adze. My eventual goal is to craft a shell age bow using authentic tools. Then I will paint it with Calusa inspired art and pigment. I will likely use a Missouri wood because A)I have access to it, and B) it has to be a green tree to use the prehistoric technique.
An experimental archeologist could keep a lot of students busy testing out hypotheses.