Cupping, crowning and dry cupping are the most common terms when it comes to moisture, or a lack of moisture. If there is water caught between the wood flooring and the subfloor cupping typically occurs, which means that the outer edges of the boards are higher than the center of the board. Crowning is the opposite - when the center of the board is higher than the outside edges. Dry cupping occurs when there is a lack of humidity in the structure and the boards appear to be cupped but there are also gaps in between the boards.

The answer to this question depends on what type of finish you have on your floors. Finish manufacturers and prefinished flooring manufacturers will have a recommended method for cleaning and maintaining your floors.

Wax-based finishes and cleaners should never be applied to polyurethane-finished or surface-sealed floors. It can become very slippery and foot traffic will tend to leave marks or blemishes

This will vary from house to house, depending on foot traffic. It is best to have the floors waxed before any discoloration appears. In general, it is recommended to have waxed floors maintained once a year.

Protecting the floor from early wear is as simple as establishing a consistent cleaning routine, as recommended by the manufacturer. This includes using a damp cloths and/or vacuums rather than wet mops, employing the use of rugs, and using plastic or felt discs under furniture to keep the legs from scratching the flooring surface. 

Color variations will be present in all grades of hardwood, as it is a natural product and cannot be controlled.

It is a common misconception that all engineered floors are prefinished. This is not the case. The majority of the engineered floors French-Brown installs are unfinished; then stained and finished on site. On the other hand, almost all prefinished floors are engineered. That said, both choices have their advantages. If you are trying to match an existing hardwood floor, you may want to go with an unfinished floor so it can be stained to match as closely as possible. Prefinished floors are factory finished and can be difficult to match.

In general, yes, but it depends on the thickness of the veneer. It may not be able to be refinished more than a few times. 

Engineered flooring has a veneer of real hardwood on the top, which depending on the thickness of the veneer, can be sanded down and refinished. Laminate flooring is a photographic image of the wood grain on engineered flooring, and it cannot be sanded or refinished.