The moral compass of humanity has moved back and forth throughout history. Evidence shows that in pre-Christian Roman and Greek times, homosexuality was accepted, as was pedophilia (noting that at a time the avg human lifespan was around 45-50yr). There has been a steady broadening of what is accepted by society over the past few hundred years, but to think its a never ending trend is silly. The rise of IS and its affect on previously moderate Arab states is an example right now where the moral compass can swing violently backwards.
As to your point: 1) I wouldn't do myself but don't have a huge problem with though there would need to be a lot of law changes to support, 2) support in theory but would need a lot of controls around it like smoking, and should have an elevated age restriction (25 IMO) as evidence shows cannabis use can damage a developing brain (which finishes at around 25yr of age).
3) I have no problem with at all, I find it amusing that some people support point 2 because 'its their bodies and it doesn't harm others' but then don't support point 3. Its their bodies and if they choice to use it to make money, and it doesn't harm others who concent to it then again what is wrong with it? Legalising prostitution empowers those who choice to practise it, by lifting it out of the black market you can regulate it, making those who practise it less vulnerable to those who would take advantage of them. New Zealand has legalised prostitution, the workers are protected by the law, get regular medical checks to ensure health is maintained, and as a result its clean, taxed and controlled.
4) People who think that pedophilia and homosexuality are somehow related are completely missing the whole thing that makes pedophilia wrong. Pedophilia is wrong because consent can't be granted by someone who doesn't have the mental maturity to evaluate all aspects of the decision. An adult of the same sex can do those things. I can't think of anyone who is actually advocating for this, there will likely be arguments over what the age of consent should be (16, 18, etc) but actual legalised pedophilia should never be supported, because it breaks the fundamental tenet of a social contract as children can't give consent due to not having the mental maturity to properly evaluate the decision. What I would like to see is a way for pedophiles to self-report and actually be supported rather than treated just as evil predators. You can't help who or what you are attracted to, all you can do is refrain from acting on those impulses, and getting support to deal with those would do far more good than demonising them so that they will never self report and get the help they need until they've abused some kid. Definitely for those pedophiles that do abuse children there can be no tolerance, but the current system almost sets them up to fail.
Summary: You can't look at a trend without understanding the differences between each step. And there is no guarantee the trend will continue.So just focus on each step and whether its right, don't reject a 'right' decision because you are worried about a 'wrong' decision 50 years down the track when they are independent of each other.