LOL my ex-gf asked the same. I don't know how could you think that? :D But the answer is no you cannot get pregnant because of this BUT you can get a disease from him if you get the sperm in your mouth so be careful!!!! If you know he is clean you could get it in your mouth but if he's not you better shouldn't do it and just do with a condom.
Absolutely not possible because mouth leads to stomach and lungs that are digestive and respiratory systems, respectively, while reproductive system is different. Pregnancy is only possible when sperms are released in the female genitalia that leads towards female reproductive system.
Gosh no! Gargle and mouthwash to be sure.