How motile is the sperm in precum and does it die quicker because its not in semen?

They work great!: They work their little tails off and are very effective. How quickly they die depends upon how hospitable their environment is. The vagina is like a 4star hotel.

Pre-ejaculate: Most studies have shown low levels of sperm or no sperm in pre-ejaculate. Sperm are usually not motile. One small study published in 2011 showed that there are some individuals with a high sperm count in pre-ejaculate. See: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3564677/