Hi celestial,
I’m certainly happy to help with “how” to choose although there are so many individual variables and unknowns with any mattress purchase that your own testing and preferences are the best way to know the specifics of “what” to choose.
Hopefully you’ve read post #1 here which has all the basic information, steps, and guidelines which will be most helpful and might help you get past some of the information overload.
You can read a little more about organic, natural, and blended latex in post #6 here. There is a great deal of misinformation on the web about the different types of latex … mostly written by those who sell one type and not another or by those who make generalizations that don’t always hold up to more detailed scrutiny. All the latex you are likely to encounter has been Oeko-Tex standard 100 class 1 (safe for babies) tested (or a similar testing protocol) for harmful substances and VOC’s and I would consider any of them to be “safe”. I would treat the choice between Talalay and Dunlop as strictly a matter of preference based on your own testing experience.
Post #3 here has links to all the forum lists that are around you in the region. You have some good options available and if you follow the steps one by one you will do well 
Phoenix