Hi dguerriero,
Only you can feel what you feel on a mattress and there are too many unknowns, variables, and personal preferences involved to be able to answer this based on specs (either yours or a mattress) or “theory at a distance” and the only way to answer either of these questions would be based on your own personal testing or sleeping experience (see mattress firmness/comfort levels in post #2 here).
When you can’t test a mattress in person or are uncertain about whether a particular design will work well for you in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences) then the options you have after a purchase to make any fine tuning adjustments to your mattress that may be necessary at a reasonable cost may become a more important part of your personal value equation.
There is also more about the many variables that can affect sleeping temperature in post #2 here that may also help you to choose materials (including your mattress protector and sheets) that will have a better chance of keeping your sleeping temperature inside a range that would be comfortable for you but thicker/softer layers of memory foam would generally have a tendency to increase sleeping temperature vs thinner/firmer layers because they will form a deeper cradle around your body which would be more insulating and allow less airflow but the tradeoff of course is that thinner/firmer layers may be less pressure relieving or less suitable for you to sleep on.
If you tend to be closer to the oven side of the “oven to iceberg range” then I would keep in mind that memory foam in general tends to sleep warmer than other types of more breathable foam or other comfort materials.
Phoenix