Of course, aside from reading the tutorials here, I'll add this:
I don't know exactly what your budget is. My guess will be that a tallalay latex over coils (less expensive than all-latex), or all coil will be the way to go. The least expensive way to find a mattress with this design will be to find a local manufacturer that has its own retail showroom. No middle man, lower cost. My experience is that somewhere about $1000 for a queen size will get you such a thing. Latex, which has lots of holes punched in it, will be MUCH less warm than memory foam (which is about as hot as you can get). Get some sort of breathable pad which can be washed such as a cotton or wool one (make sure it's washable).
Given that a mattress essentially has two layers -- the support layer (coils, latex or memory foam) and the comfort layer (cotton, polyfill, wool, etc.), you need to look at which has the best cost/performance for you. Coils are the least expensive material, but if you go with all coils, you REALLY need to pay attention to the quality of the toppers and pads (What's going on top of the coils). You can always buy these things as add-ons to make the bed more comfy. You need to make sure that your spine is aligned and supported when you side sleep (or back sleep), but also need the comfort particularly due to your weight and that you sleep in the side. You can make a bed softer, but you can't stiffen it up. Too soft in the support, and your back won't be aligned and body won't be at rest when you sleep. Tallalay latex is particularly cushy unto itself (and is made in different stiffnesses), so great for alleviating pressure points. It makes for a very popular and value-oriented comfort layer (though more expensive initially than polyfill).
Latex is more expensive than coils, however, so using it in JUST the comfort layer than using latex for the whole mattrress makes for a more economical option. If there are cheap quality (polyfil, for example) comfort materials on top of the coils, then you'll quickly lose the comfort aspects of the mattress because they break down more quickly, and you'll soon be sleeping on top of metal coils. For many, though, you can replace added on toppers and pads less expensively than buying a whole new mattress (Coils tend to last quite a long time -- longer than the comfort layers).
Of course, if you can't afford $1000, you may find yourself having a mattress that feels okay now, but not so much in a couple of years or so.
I wish you the best in finding a mattress which is comfortable and healthful.
