For example, the layout of one kitchen might lend itself to adding a dishwasher easily.

The simplified layout eliminates the need for excessive finger scrolling, putting everything at our fingertips.

Why give burglers a layout of your house and your belongings?

Next I intend to cross check the calculations (esp. taxes) and simplify the layout.

I don't have a magic wand to help you move forward but I would just lay out your possible options: 1. 

. - if you need two stairwells and an elevator, that will of course drive costs way up and it also eats into your floor plate area and can crush layouts on a smaller building, possibly turning your small CMX2.5 lot you'd planned to build 5 stories on into what may as well be a CMX2 lot and allow only 3 stories, since you can't actually fit 2 stairwells, an elevator, a hallway all the way through from front to rear, a small lobby, a mail room, etc.

An existing kitchen layout might work well for adding a dishwsher or microwave hood for example allowing it to be made functionally modern without a major rehab.

Dimensions and layouts on these are mostly standardized so you shouldnt have any problem unless the existing cabinets are custom built for the space.

Layout reminds me of small time share condos but the other condo complex next door does not resemble this one at all.

As long as you have a good layout, I feel there is more opportunity in the older home space, IF bought at the right price.