I will agree with much of what has been said. You are keeping inverts successfully, so you are doing something right. One major issue is the accuracy of the equipment you are using. If the test is faulty then the actions that you take to correct a problem is going to cause problems instead of fix them. Be sure of the equipment / tests you are using. I think earlier on somebody had offered to come test your water. Take them up on the offer- they may spot something else that nobody has noticed and that you could only see in person.
Next, as to a million different suggestions- you will find that in this hobby. Everybody has their own way of doing things from those who use no skimmer to those who use Zeovit. Neither is wrong. How to acclimatize fish? Well, on both sides you will find people very adamant that their way is the “right” way. Try to remember that neither will kill everything you put in the tank or nobody would follow it. It is like that with most disagreements. Drip or don’t- one may cause slightly less stress- but neither will guarantee dead stock (but do keep an eye on the temperature.)
R/O water- nice but if you are doing 15% changes not a requirement. Not using it may cause some other issues with algae or the likes- but as has been mentioned- many people are successful without. It may not be ideal- but keeping saltwater fish was popular (though slightly more difficult) before every home “needed” a filter- and the last tank that I kept I did not use R/O and I did not do huge water changes. Nothing was what I would consider stressed or unhealthy.
Finally, concerning issues such as S.G and temperature, I use
http://www.ronshimek.com/reef_aquaria.html In the article on salinity / temperature he gives the actual temperatures and salinity of the ocean around the world. I don’t know if he outright states what is best- but if you can think he does make it so you can draw your own conclusions. Then you just have to be confident that you are providing the best conditions that you can and that most closely match natural conditions and ignore any well meaning advice. Good luck.