Was Don Carlos Buell a slave owner?

North Slave owners did pay their slaves, but south slave owners didn't. See the following link.

they were looking for strength and physical looks. They also were looking for how hard a slave worked.

Yes. Females slaves were raped by owners to give birth to Mulatos, which were slaves as well.

The purchased them at slave auctions. Owners that had more slaves than they needed, and those bringing them from Africa would sell them at slave markets.

Slave owners sold their slaves to earn extra money. They often bred their slaves so that they did not need to waste money on buying more slaves. When the baby slave was born, they were sometimes sold...