Unfortunately, Rhi, the Bible does say that people who practise homosexuality are not in God's kingdom. This is stated in 1 Cor 6:9 and 1 Tim 1:10. So that answers Sassy's point, and means that Christians need to abstain from this as they would abstain from adultery - if they want to be living for God. The passage in acts where the apostles decided which aspects of the Mosaic law needed to be kept by Gentile believers, is to do with those things that God prohibited in Leviticus 17 and 18 which applied to Israelites and non Israelites living with them. The connection should be clear.
But in answer to your second point: yes, people desire sex and that desire is essential to continuing the human race. But there are obvious limits beyomd which the sexual instinct needs to be restrained, and one of those is with homosexual urges. There is a reflex in men which deals with excess build up of sperm. Therefore there is no biological requirement for a man to have sex with another person. I don't know if the equivalent happens with women, and the OT mentions nocturnal emissions as being normal and not sinful. I think the area I need to think through more is how homosexual relationships cause harm. I was friends with a gay bloke and a lesbian at one time, and I was aware that I was personally affected by their homosexuality, because I fancied the lesbian and the bloke fancied me... A right muddle!