The Levitical law was not passed down to the people directly from God (gasp!). The people came up with their own extensive set of rules, and by following them attempted to present worship that the Most High God deemed worthy to receive. And of course, as he did with Abraham (who had no such set of rules in existence), God counted their faith as righteousness.

On homosexuality in Leviticus, there are 2 reasons why it is called an "abomination". 1. They had a real problem with infant mortality, as did all people in those days, so the population was constantly under threat. If people were having same-sex relationships instead of hetero, that would decrease the race's chances of survival. Of course there would be nothing wrong with having homosexual relationships on the side, but for the 2nd reason. 2. People believed that a baby was contained within a man's semen, and a woman's womb was simply a place for the baby to grow. So for a man to ejaculate anywhere other than a woman's vagina would be effectively considered to be an abortion. In the laws on ceremonial cleanliness, you may also note that if a man had a discharge (ie. nocturnal emission or otherwise "jizz in my pants" moment), he had to be considered ceremonially unclean for a period of 7 days. Of course it was not called an abomination or sin, because it could not be controlled.

So... read Leviticus, but treat it like a history book more than anything else. The words recorded within have nothing to do with anyone's salvation.