Thanks for that interesting essay. Normally, it's said to be a sign of "modern" people to be open-minded to all kinds of sexuality. Although I am neither a conservative nor an adherent of a specific religion, I have my moral problems with sexuality but they sometimes differ from yours.
Yes. I take it as axiomatic, again, that sexuality is bad independently of happiness and suffering.
Wow! That's really tough! I wouldn't claim that myself because I couldn't prove it but sometimes I feel alike because sexuality causes immoral feelings. Sexual desire means to me to desire someone's body to instrumentalize it for your own pleasure. I have problems to ally sexual desire with love, especially with agape. I find it hard to sexually desire somebody who I do respect.
If I consume pornography, I am not able to regard nude women as something worthy of moral consideration whereas if I am not arroused I never feel that disrespectful about women. I think my moral development would be more progressed if I was an asexual.
In my mind, the least objectionable sexual practices on the second dimension are marriage-bed, missionary-position-type activities, and there is a gradient of abnormality and revulsion that includes masturbation, contraception, pornography, etc. The first dimension includes the consequent misery of sexual activity, encompassing sexual frustration, unrequited love, broken-heartedness, sexually transmitted disease, rape, etc.
I don't understand what problems you have with certain sex-position (non missionars-position-type activities), masturbation (Okay, here I am open to discuss) and contraception. To me as a wicked, faithless, liberal European this sounds like the remains of a typical puritarian upbringing. All I would miss is the sentence: "God hates homosexuals."
In my opinion, the most important problem with sexuality is that of involuntary pregancy (I have a problem with bringing people into being at all, but that's another point). I think involuntary parents take less care of their children what makes them less capable of taking care of others and gives them worse chances in life. I' ve found a document that claims that the liberalisation of abortions has lead to a decline in U.S. crime rates.