I'm with you on wanting the least amount of clutter in the backsplash area as possible. I think many people do just put them on the wall...mostly because that's "where everybody puts them." But I think you could have them both cabinet mounted maybe. I would talk with your electrician about it.

I placed mine at 12", which is right inline with the 12" uppers. It's a small 6" light with a 3'0" window. Not that it matters, but I ended up cabinets 7" from window edge, leaving me room to have 3-1/2" casing around window. Still left a few inches on each side of casing so cabinets are not right against trim.

once you decide on the sink placement that will dictate the mirror placement unless you just go with very larger mirrors that are centered to the whole counter area. but if you did that you would maybe consider sconce lighting to over mirror.

Personally, I would go with the recessed light - less is more, and like you said, not so cluttered feeling (and trust me, I am wild for pendant lights!) In the middle of our kitchen remodel but the lights are in and we have the recessed light over the sink on a separate switch which gives options for all lights or just a really good one over the sink. First lamp seems simpler and again (just my likes, not yours!) I like the first one better in your space. HTH (PS Working on pendant lights over island - have a wild yen for Steam Punk lights, but y'all may hear from me later. :) ).