This means that you were infected with hepatitis C at some point but your body was able to clear (get rid of) the infection, and so you no longer have the virus. Unfortunately, if you are exposed to hepatitis C in the future, you can be re-infected.
Some people never clear hepatitis C and so the virus is still detectable in their blood. This means they are at risk for the complications of having hepatitis C, for instance iver damage, and that they can transmit it to others. Luckily there are well tolerated medications that can treat hepatitis C in as little as 8-12 weeks.
It is possible to spread HPV from the penis to the throat during oral sex, but it is rare.
As for ways to protect yourself, condoms can decrease the risk of HPV transmission. There is also an excellent vaccine that protects against 9 of the most common strains of HPV -including 4 high-risk strains and 5 strains that can cause warts. Its recommended that all men and women <26 receive this vaccine.