Thanks for your input. Here is a photo of the bike by itself. I haven't measured the seat post, but based on the geometry chart, my current saddle height is approximately 18cm above the end of the seat tube. The stock stem is 100mm with a 6 degree angle. It came flipped up, and the overall rise of the stem is 22.9 degrees. The bars are compact with a reach of around 85mm. Therefore, the stock cockpit is pretty short, and there should be room to add more reach if I need it.

This frame is a 56cm. The calculator at Competitive Cyclist recommends a 54cm frame for the Eddy and Competitive fit, or a 56cm for the French fit. Every other online calculator that I tried recommends a 56cm, so I am reasonably sure that a 56cm fits me. With the stem flipped up and 30mm of spacers, the saddle to bar is 4cm. Flipping the stem and removing all the spacers will drop the bars another 5cm.

My flexibility is quite poor currently, but I am working on it, so I hope to be able to gradually get into a more aero position. I can certainly bend my elbows and lower my torso for short periods now, but the more upright position in the photos is my default and most comfortable position.

As for the OEM saddle, it is a Fizik Arione R7. The cheapest retail Arione is the R5, so the R7 ranks below that, but surprisingly, it fits me quite well. It took some time to get used to the flat shape and firmness, but after the adjustment period, 3-4 hour rides have been no problem.