Hi Mathias, answering out of turn.
The more upright the riding position, the farther you need the saddle behind the crank, also, generally farther down in elevation.
More aggressive riding position, the taller you ride over the crank - here are two extremes.
Reach is mostly controlled by your torso length, and finding a comfortable position that lets you keep your elbows bent and wrists straight.
When you find your perfect bike, here my '75 International (rebuilt 5 times in 4 decades), use it for a measurement reference, and make small adjustments from there.