Hi Uncafeaulait
Welcome to our Mattress Forum! 
I can certainly understand the sense of overwhelm with the many things you have to consider to ensure a good night sleep but the best suggestion I have is to work through it step by step and revisit the mattress shopping tutorial here which acts as a reference to help you find those that have the knowledge and experience to help you make an informed decision and gives you the basic information you need and will save you having to sort through all the many forum postings. Once you are armed with the basic information and tools you need … you have the ability to reach out to any of the Expert Members of our site who can help you make good choices that are suitable for your needs and preferences and are not only interested in selling you whatever they can but have your best interests at heart.
Unfortunately, in regards to your current mattress…. the major brands such as Sealy/Stearns & Foster, Simmons, and Serta all tend to use lower quality and less durable materials in their mattresses than most of their smaller competitors that will tend to soften or break down prematurely relative to the price you pay, which is why I would generally suggest avoiding all of them completely (along with the major retailers that focus on them as well) regardless of how they may feel in a showroom along with any mattress where you aren’t able to find out the type and quality/durability of the materials inside it (see the guidelines here along with post #3 here and post #12 here and post #404 here ). And as you discovered, Mattress Innovations doesn’t offer any meaningful specifications on their website in order to make an educated analysis of any of their products. But there is a list with some other options or possibilities I’m aware of in and around the Dayton, OH area (subject to the quality/value guidelines) in post #5 here. The best way to go about your next purchase is to arm yourself with all the information and expert help you can get to make an informed decision.
It is always nice to upgrade from Queen to King for partners with temperature regulation issues as well … to have more space and also put some distance between you and the “furnace” when the heat is on. Temperature regulation issues have been extensively discussed on our forum but you can peruse post #2 here that discusses about the many variables that can affect the sleeping temperature of a mattress or sleeping system and can help you choose the types of materials and components in your next mattress that are most likely to keep you in a comfortable temperature range. In very general terms … the materials, layers, and components of a sleeping system that are closer to your skin will have a bigger effect on airflow, moisture transport, and temperature regulation than materials, layers, and components that are further away from your skin and softer mattresses or foam toppers will tend to be more “insulating” and for some people can sleep warmer than firmer versions of the same material.
Memory foam does a very good job at minimizing motions transfer, but (as you discovered) it will generally be the least breathable and most insulating of the foam comfort materials, so temperature can be an issue.
Both options you are considering are great quality/value choices from two of our Trusted Members of the site, and I certainly aggree with you that It would be well worth doing some local testing on a mattress that has latex in its uppermost comfort layer and experimenting with a few firmness options will help decide if you’d like a latex mattress.
You are wise … “mass reviewing” of any product would raise a red flag for me too and this would not be a factor that I’d base my decision. I’d also keep in mind that any layer placed between the mattress encasement and yourself will of course impact its feel and temperature you are experiencing while sleeping. You may wish to read through some of the popular types of mattress protector options as listed in post #89 here . There are some that use wool in their construction as well that may be of interest to you as well…, a washable wool mattress pad like the St. Dormier might be something to consider.
Unfortunately choosing a pillow is like choosing a mattress and there are too many unknowns, variables, and personal preferences involved in choosing a pillow to make specific suggestions or recommendations for someone else. There is no single pillow that is “best” for any particular situation or “symptom” and it is good to remember that the main goal of a pillow is to keep your head and neck in good alignment in all your sleeping positions. Which pillow does this for any particular person or on any particular mattress will vary widely from person to person. In other words … a pillow that works well for one person with upper back, shoulder, or neck issues may not be suitable at all for someone else with similar issues.
Pillows are also a very personal choice and different people will have very different pillow preferences or different opinions about what they perceive as firm and soft or the general type of pillow that “feels” good to them but some of the information in the pillow topic here and the posts it links to can help you choose a pillow that is the best “match” for you and the mattress you are sleeping on.
I’d be interested to find the results of your testing and the progress you’ve made I search for a suitable mattress.
Phoenix