I use to raise both holland lops and mini rex.
I love them both, but most people are partial to the fur of a mini rex.
They are very easy to litter box train, but the best boxes are the ones made for bunnies that have a tray with wire over it. (they tend to sometimes rat cat litter and will sit in shavings.
As far as males vs female. Some males will spray just like a cat. When coming into breeding age, about 6 months they tend to get moody. It is best to get them fixed then they usually won't spray and seem to be better behaved.
Just like yorkies, its best not to purchase from a pet store, most bunnies that go to pet stores are those that are of low quality or sick. You can also find a rabbit show in your area by going to American rabbit breeders association.
Good luck!