The best way to get the right temperament for your needs is to work with an excellent, experienced breeder who knows her lines and her puppies. She will have a very good idea of the temperaments in the litter. Good breeders also often temperament test their litters. Temperament testing is NOT fool-proof, but it gives a little more data and is often a good check on what the breeder is seeing in the puppies.
Trying to figure out temperament based on a visit (or even a few visits) can be a fool's errand. ALL puppies (unless they are WAY outside the norm) are wild and playful some of the time, and sleepy and cuddly other times. It's the nature of young animals. It will depend on when you see them. It's really, REALLY important to be honest with your breeder about what you want, and then trust her judgement. If you don't think you CAN trust her judgement, find another breeder.
As far as others have said, Havanese colors can be pretty tricky. Sables almost ALWAYS fade to some extent. Some less, some more. Many end up being essentially white dogs. Chocolates are also likely to fade, especially chocolate sables. Reds are more likely to maintain their color, though red sables are born VERY dark, then lighten somewhat. Still not as much as other sables, though. There is also a color called "brindle". In this color, the puppy will have black and brown "tiger stripes" at birth. They fade just the way sables do, and when their coasts start to get a bit longer, you can't see the stripes anyway. The way they do often differ from sables is that most brindles retain a black or dark mask around their mouth, nose and eyes.
The best bet in terms of remaining a specific color is black (or black and white) from a line that carries neither the silver gene nor the belton gene. The silver gene modifies the coat by adding white hair over time. Some, like my Pixel, have just a TINY sprinkle of white hairs that you have to look close to see. Others, like her sister, turn the color of a silver poodle. Someone already explained the belton gene. This one is tricky too... Some, like my Kodi remains essentially a B&W dog with a SPRINKLING of small black stripes. (which show most when the dog is wet) On others, the belton markings are so dense that all the once white areas become sooty grey as they mature. My Panda is what is now as a B&W with "clear" markings... meaning she doesn't carry the belton gene, and has no black spots sprinkled in her white area.
In general, you can tell SOMETHING about whether a puppy will lighten by looking around their eyes, under their arm pits and the roots of the hair on the coat. If the puppy has light "spectacles", or if the hair is significantly lighter in the other areas mentioned, the puppy will CERTAINLY lighten substantially. Silvering (which can be a modifying gene in any color, BTW, and I am pretty sure is the cause of Truffle's substantial lightening) can be obvious at the time puppies go home... or not. If they have only one copy of the gene, you may see no signs of it at that age. You can rarely see belton markings (again, this gene can modify color on ANY Havanese... it's just most obvious on the B&W's) at the time puppy's leave for their new homes. You really have to depend on the breeder knowing her lines. If one of the parents is a belton, it's likely that the B&W puppies in the litter will be too. How much they darken is guess-work.
All of the above is to say why it is SO important not to pick a Havanese puppy based on color... What you see is probably NOT what you are going to get by the time the dog is an adult!
The only colors definitely to be avoided by breeders are blue (which is not an allowed color) and merle (also not allowed, and linked to some major health issues) However, a reputable breeder is VERY unlikely to have merle puppies cropping up in their litters. A FEW good breeders have some Cuban stock with does, legitimately, carry blue. So they might want to place a blue puppy in a pet home, and there is no harm in that.