We did a kitchen very similar to yours and went thru a similar dilemma last year. Ended up with a large sculptural drum pendant with a diffuser in the centre of kitchen and led recessed spots above island. Spots and drum are on two separate control switches with both fitted with dimmers. Led can be harsh if not able to be dimmed. Plastic on our new dishwasher went from blue to yellow overnight on first day and we had to ask for dimmer. Led great as task lighting but postion them so your head doesn't block light as you work. We play with lighting depending on whether we are working or relaxing. Money we saved on three pendants was spent on one drum.

That looks awesome CP. I love the door and the timber cladding as it is (you are thinking of staining it??). I also love your slate tiles- a pressure wash and a reseal will bring them back to new. I think they could work well with what you have there. Perhaps just 2 led down lights over the door? Even a black surface mounted down lights would look cool and blend with your look. What ever you do- I'd be keeping it simple. Yes- the stairs would ideally go all the way across, it's do-able (like anything), but it would cost you $$$, and frankly I don't think the expense would be totally worth it. A big pot of bamboo or fiddle leaf in the 'dead corner' down between the stair and deck would break it all up and add some green

You need to get an electrician in to advise and quote. Not easy to retrofit unless it is a suspended ceiling. Spacing depends on the coverage of selected down light and the ability to install in certain locations. They need a cavity to be installed into. The electrician will need to consider beams and joists that block paths for cables, if they are timber joists then they might be able to drill a hole through. There will probably be a lot of holes in ceiling that will need patching when you are through.

Probably would need timber staircase but have you thought of a sisal runner up the stairs as an alternative to carpet? It keeps the noise down and is very hard wearing