I agree with your general approach of looking at the Old Testament in its proper context. I also agree with the way in which you categorize different laws and in why some may not apply to us today while others might.

However, it seems that in some places, you have to ignore certain parts of the passage in order to make the passages you are using fit your theory.

For example, you say:
At the end, the Apostles realised that it was only two aspects of the Mosaic law that needed to continue, keeping away from idolatry and sexual immorality (Acts 15:28-29).

But when we read that passage, we find what you would call Holiness Laws included within it. Two of the requirements for kosher meals are listed there. The law against eating blood comes from the Old Testament belief that "the blood is the life and you should not eat the life with the flesh" (Deuteronomy 12:23). The rule against eating animals that have been strangled comes from the same idea, that you need to drain the blood before you eat the animal. These are clearly laws of a ceremonial nature, or what you term in your essay "Holiness Laws". This doesn't match the claim you make about the passage.

With this in mind there is no comparison between God’s laws on sacrifices, feast days, kings, slaves, clothes, food etc… and the laws regarding sexual immorality and idolatry.

Yet there was one in the very passage you used as an example.

It is worth noting that with the exception of homosexuality and possibly the menstrual period issue most people in the modern world would still agree that this list still applies as a correct standard of morality.

If you are going to use the passage to support your point, you can't just say "with the following exceptions". You are basically asking us to ignore the parts of the passage that don't fit your theory.

It is also worth observing that until the historically recent (and still debated) acceptance of homosexuality, they would have agreed with all of it (again, not sure about the menstrual issue) and that is has only been because of pressure from homosexual persons that this has changed.

This statement is historically inaccurate.

As much as I dislike citing it as a source, in this case wikipedia truly is a great resource since this article has quite a few references and gives a good historical overview:

http://en.wikipedia.org/wiki/History_of_homosexuality

It seems to me that in finding passages that support your point of view, you are glossing over, ignoring, or perhaps bending over backwards to explain away the parts of those same passages which don't fit that point of view. I'm not sure that is any better than what those who ignore, gloss over, or bend over backwards to explain away the bible's rejection of homosexuality do.