Personality depends on the owner, the temperament of the parents, and the dog itself! You can tell their personality when they're puppies, more or less. Is the puppy playful and fearless? Or is a little more shy and cautious?
Unfortunately color is really hard to determine in the first few months. You have to look at the parents and the pedigree (if there is one), then you can get a general idea of what colors your pup is most likely to end up with.
That's terrible about Lexi.
Did the breeder say what she died from? (Hope that isn't an insensitive question! If it is, I'm really sorry.)