HIV is no risk for Oral exposures
1. oral sex is low risk
2. that is up to you. to be 100% safe yes, but without symptoms good chance you don't have anything, but again that is your call
3. most of the time yes. Gonorrhea about 90% of men show symptoms(2-30 days post), NGU-yes(7-14 days post), syphilis-yes(average 21 days post), herpes-probably.
4) see above