No, it is perfectly safe. (Excluding any potential diseases from the donor)
a girl is most likely to get pregnant when they are on their mentral cycle. it always important to use protection whenever you have sex. During the middle of ovulation for the month
You would have to be very unlucky, penetration is usually necessary. But don't take chances. Definitely a chance. What you are calling "pre-cum" is actually the stuff that is needed to make a baby. If this gets on you and finds its way home you will get pregnant.
Relax and enjoy sex, make sure that you have enough foreplay happening too some women are just tight but the vagina does balloon out to some extent when sexually aroused...hope this helps, Good Luck and God Bless!!!
there could be a chance but i would say more than likely no because it takes about 7 days for you to be at your highest fertile stage during ovulation but all women are differrent so it just depends on your ovulation stage. if you have any signs of pregnancy during the next few weeks you should take a pregnancy test just to be sure. hope i was of some assistance to you. if you have any other questions just ask and maybe i can help.