Oral anal is not a risk of contracting HIV.
Any unprotected anal sex carries a risk of HIV infection,anal secretions or not.
Yes anal secretions are infectious for unprotected anal sex.
HIV from anal sex is usually from the abrasions to the rectal walls. Just use a condom to keep yourself safe during anal sex. Fingering and rimming are fine too as far as HIV goes. There are other diseases that you can get through rimming, but we all take some risk in life.