after you clean the head of your penis you need to re-cover the head with your foreskin.the foreskin protects the head of your penis from the prickly pain you are having.
Issues one by one:
1) Keep it clean. Soap and water should do fine. No-one is going to want to get intimate with that if you don't keep it clean ;)
2) Sorry, don't know (I'm circumcised myself)
3) Is that length erect? Also, I'm not sure if there's any industry-approved standard on where you measure from - measuring at the side will probably be an inch different than along the top. In any case, I'm pretty certain this will have no effect on your fertility, the sperm are made in your balls so the size of your penis won't affect that. When it comes to sex, there are some positions that help you get in deeper, which may work better if you're not so big - doggie is good, particularly if your partner is kneeling at the edge of the bed and you are standing up.