No they are not 100% , I think the official figure is 97%. Why? They break, some though very very rarely may be imperfect, and the condom doesn't conver the entire penis, so the base of the penis is still susceptible to things like herpes.
Hand to genital contact....
Not a risk for hiv I believe as it doesn't survive long outside the body, but herpes can be passed this way if she has an active outbreak and wet hands. Genital warts also possible. Bacterial like gonnoreah and chlamydia theoretically possible. Though rare. Thrush can also be passed on like this.
Generally, chlamydia doesn't like living in the throat, but gonnoreah will quite happily live there for about three months. Things like ngu, can also be passed, as can herpes. By the way, just because she doesn't have a cold sore in her lips means its safe. The virus can still actively shed when no sores are present. Hiv I been told is practically impossible from owo, though theoretical if there is a lot of blood involved and the person has cuts or sores or recent dental work.
If something was going to show, it would be within two weeks. The window period for urine testing is also 2 weeks coincidentally. So while it may be low risk, there are a fair few people who have caught something from owo , me included, hence I know all this from reading up on things!