Hi PFISTO,
Just in case you haven’t read it … post #1 here is the best place to start. It will give you all the basic information and general guidelines you need to avoid the information overload and “doubl talk” and “cut through” all the conflicting information that you will be exposed to when you are looking for your “perfect” mattress.
You don’t need to 'study" any of it because it will help you recognize who knows what they are talking about and who is just interested in selling you whatever they can. Finding an “expert” that you can trust and will help you make the best possible choices is much simpler and more effective than becoming one yourself because they already know and are willing to share what you would otherwise need to learn 
Post #7 here and post #2 here (which are centered around Monroe Township, NJ and New York, NY respectively and have a lot of overlap) include the better options and possibilities I’m aware of in your area.
Phoenix