2) How important is it to have a variety of colors throughout the home?

Painting houses a neutral color is the easiest and least expensive way to get houses rented or sold. 

Or keep the uppers and lowers the same and contrast the island color. 

All foreclosures are based on gross fraud, forged signatures,fake documents, corrupted judges who are criminals working for the bankers.The same goes for the attorneys.This country doesn't have the lawyers, and public officials are not following the law.Not the common law not even their own fake, UCC code color of law.BAR attorneys are foreign agents trained to destroy American people and American Constitution!

As long as you follow the rules like lawn maintenance, paint the fence a certain color, keep the house a decent color you'll be fine.

I ask them on paint color, hardware, floor stain/finish etc.

It's made by a company called general finish, Java is the color.

I will spec materials/colors/repair method when I feel it needs to be done a certain way or I want something different/special.  

Or make him a gift of a key ring that would hold some sentimental value to him and then color code each of the 3 keys he needs for entry to the apartment and place on said keyring.

The majority of the house has a lighter colored LVP which has unfortunately been discontinued.