So I would prefer two opposite rows instead of the U-shape. With the corner cabinets, you either have dead storage space or high costs with swivel pull-outs, etc. Visually, I also find two rows better. Whether the seating area is a good idea, I don’t know. You really have to plan it in detail to know how big the passage will be.
I would go directly to a kitchen studio of your choice and plan a kitchen. Only that way will you learn what you need to pay attention to. Then you will also know where water, electricity, etc. have to be installed. It’s too late afterwards. As an alternative to the kitchen studio, you can also try the Ikea kitchen planner yourself. But I don’t recommend it because you lack expert advice.
Faucet NEXT TO the window, etc.
Nope, there are also good folding faucets. I ordered one myself.
One hears about horrendous delivery times for kitchens; does it make sense to buy the kitchen "now" and schedule delivery/installation for September 21? Is that even possible? What if the construction is realized 1-2 months earlier or later than planned?
How did you plan the delivery and installation?
You can order the kitchen anytime, but the final kitchen is usually only measured when the walls are plastered. Never order a kitchen blindly based on raw construction measurements. That will go wrong.
What would be horrendous delivery times for you? I think 6-8 weeks was realistic for me with Nobilia (a simple kitchen studio). How much time do you have between the finished plastered walls and moving in? If necessary, you can survive 2-3 weeks without a kitchen.