A donor's semen could be infectious for a disease such as AIDS or Hepatitis at the time of his donation, and several months could pass before any tests or symptoms would reveal its presence. Most sperm banks freeze and quarantine the sperm for about six months while the donor undergoes repeated testing for these STD's. Specimens are released when tests remain negative at least 180 days after the donation. This survival time is highly variable and can range from several months to 15 - 20 years. It has little to do with the sperm being frozen.
Male sperm are generally faster swimmers than female sperm.
However, male sperm also die faster than female sperm. Since frozen sperm only live in the female genital tract for about 24 hours after thawing, this would reduce the chances of pregnancy altogether. The average is 8 months for all age groups combined. If you're approaching 40, you may want to consider a fertility evaluation before you even start inseminating. Statistically, intrauterine insemination combined with treatment, if indicated, will increase the chances of conceiving sooner for this age group.