1. Yes, laura_girl is right. That is why it is better to wait every other day or so to have sex during ovulation; to let the sperm count build up.
2. No, it is physically impossible to get preg. Through the anus.
3. Sex is sex, doesn't matter which position it is done in, it all goes the same place.
4. Symptoms usually do not appear until 4-6 weeks. Some women, however, have stated that it has happend that early. All women are different.
5. As far as laying down, I am not sure. But, I would think it might help to elevate the pelvis because any help is good help. Gravity works in mysterious way.
I hope that I helped. Good luck!!!!!!!!!