A: Assuming the harassment involved is sexual in nature...or perhaps because of some other protected class such as age, disability, religion, etc., you should probably file a charge with the EEOC. Here is a link: http://www.eeoc.gov/employees/howtofile.cfm You only a short time in which to file a claim, so if the harassment is something protected and the employer does nothing, you should not delay in filing a claim with EEOC or contacting a lawyer.
A: It means the opposing party has voluntarily dismissed their claims. The "non suit" can be "with prejudice" or "without prejudice". My guess is it would be "without prejudice" which means the opponent can refile the case as long as their claims are within the statute of limitations.