Hi nico4321,
Welcome to the Mattress Forum! 
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. All foams and materials insulate to a degree, and a softer mattress that allows you to sink in more will tend to feel warmer and also allow less area to be exposed for efficient heat dissipation, versus a harder feeling mattress that doesn’t allow you to sink in quite as much. As for foams, latex (specifically Talalay) tends to be the most breathable, followed by polyfoam and then memory foam.
Overall, it’s not really possible to quantify the sleeping temperature of a mattress for any particular person with any real accuracy because there are so many variables involved including the type of mattress protector and the sheets and bedding that you use (which in many cases can have just as significant an effect on sleeping temperature as the type of foam in a mattress) and on where you are in the “oven to iceberg” range and because there is no standardized testing for temperature regulation with different combinations of materials. There is more about the many variables that can affect the sleeping temperature of a mattress or sleeping system in post #2 here that can help you choose the types of materials and components that are most likely to keep you in a comfortable temperature range.
Regarding cooling memory foam claims, you can read more about phase change materials in post #9 here and at the end of post #4 here) and you can read more about the various different types of gel foams in post #2 here. In general terms gel foams will tend to have a temporary effect on temperature while you are first going to sleep until temperatures equalize but have less effect on temperature regulation throughout the course of the night.
Graphite itself is a very thermal conductive material so it would make sense that graphite infused memory foam would be a little more effective than the gel that is more commonly used but it would also depend on the amount of graphite that was in the memory foam.
[quote]I also tend to be sensitive to smells/off-gasing[/quote].
If you choose a latex product, it has a smell that some people describe as “semi-sweet” or vanilla-ish. This is normal and tends to dissipate in a few weeks. It’s important to note that not all odors are VOCs, and not all VOCs have odors (see here). If you are very sensitive to odors, as some people are with Multiple Chemical Sensitivities (MCS), an odor, even one that isn’t harmful, can be unpleasant. Memory foam tends the be the material that most people complain about as having an odor that they describe as unpleasant.
You can see some of my more detailed comments about the overall sleeping environment microclimate earlier in this post, but it would be logical to assume that more air will move through a finished mattress using a pocketed spring mattress than one using all foam. Of course, the thicker the comfort layers are on top of that spring unit, the less that this increased air circulation would be noticed.
Just for clarity, I don’t make recommendations for stores unless they are a vetted member here of the site. The fortunate thing is that there are many members of this site (which means that I think very highly of them and that I believe that they compete well with the in the industry in terms of their quality, value, service, knowledge, and transparency), who are extremely knowledgeable about latex and different configurations, and I would not hesitate to recommend them for your consideration. You can look at this listing of site members offering latex products.
I have had to discontinued the provision of listings of potential retailers in various geographic regions (unless they are already approved site members) because of the difficulty in maintaining such lists in a retail landscape that is constantly changing, and most importantly the confusion it was creating with the consumer members who incorrectly assumed that these businesses had indeed gone through the strict vetting and qualification process that is part of becoming an approved member of The Mattress Underground. Such an assumption is unfair to both the consumers seeking assistance, as well as the very businesses and manufacturers who have indeed qualified the be members here of The Mattress Underground.
You can perform a forum search on Buffalo and see what other businesses have been discussed in that region which may be helpful to you.
Whatever business you’re considering, I would always confirm that any retailer or manufacturer that you wish to visit is completely transparent (see this article) and also make sure that any mattress that you are considering meets the quality/value guidelines here.
If you have any questions about specifications or certain products you discover, feel free to post back on the forum and I’ll do my best to be assistive.
Hopefully that gives you some good information to get started.
Phoenix