I would have some contrast between my wood kitchen cabinets and the new flooring but I also think the existing and new floors must blend together.

I won't mind having wood floors provided that I will use backsplash tiles that will complement the kitchen and aside from that, paint colors matter to combine the elements in your kitchen. Neutral colors always do the trick.

Just for fun I was reminded of this kitchen floor when you mentioned painting a design. Not sure if this fits your style and cabinets are obviously different, but this is a pretty cool kitchen.

On the adjoining room question, I think I'd at least try to match the wood stain as well as you can especially if you have an open floor plan or the rooms flow into each other. Sometimes you can soften the transition by creating a border around the room. I have a really old home through the years basically every room is a little different - even when we refinished and stained everything the same color some rooms came out different than others. Small variations in wood floors do not bother me that much.