of the two, I'd choose the round one to go.

IMO no need for pendant above the sink and those are like you tried to match and missed. I woudl however tell you to have all the bulbs in all the fixtures and pot lights to be the same I like LED 4000K but 3500K can work but all the same . Edison type buls are horrible for lighting everywhere there is a reason they disappeared .

I don't think you need anything above the sink. More isn't always better - sometimes it is just more.

I definitely would not place a picture in the blank space over the window.

It is perfectly okay to leave it as is.

I add a great window treatment instead.

I actually have nothing, just the ceiling pot lights, like you.

I am craving a great window treatment:-)