Hi mugwump,
You are certainly looking at some good options 
If you were only sleeping on a single layer and if they were both the same firmness and ILD then Dunlop is denser and would be firmer than Talalay in the same ILD once you compress it more deeply than 25% (it gets firmer faster than Talalay when you compress it more deeply) but firmness isn’t the same as support and this doesn’t mean that it would be more supportive or more importantly would keep you in better alignment in any particular mattress. It would really depend on the specific combination of materials in each one and which mattress your testing indicates keeps you in the best alignment in all your sleeping positions. There is more about the relationship between primary and secondary “support” and alignment in post #2 here and in post #4 here.
The choice between Talalay and Dunlop in either support layers or comfort layers is primarily a preference choice. There is more about the differences between them in post #7 here but once again it would depend on the specifics of the materials and overall design of the mattress and which one your testing indicated provides better pressure relief. Nobody else can feel what you feel on a mattress and there are too many unknowns, variables, and personal preferences involved for anyone else to know which mattress is the best “match” for you in terms of PPP based on specs (either yours or a mattress) or theory at a distance (see mattress firmness/comfort levels in post #2 here).
In most cases … Talatech would refer to blended Talalay. “Natural” can refer to either 100% natural Talalay or blended Talalay (Pure Latex Bliss for example which is owned by Latex International refers to their blended Talalay as “natural” and their 100% Talalay as “all natural” so it can be confusing). There is more about the different types and blends of latex in post #6 here but the most reliable way to know which type of latex is in a mattress would be to specifically ask the manufacturer or retailer about the type and blend of the latex in a mattress you are considering.
Not in terms of quality or durability no but the thickness of the comfort layers are one of many factors that can make a difference in which mattress is the best “match” for you in terms of PPP.
The quality of a mattress depends on the specifics of the materials in the mattresses you are considering and the name of a manufacturer has little to nothing to do with the quality/value of a mattress. Having said that … Parklane is a member of this site which means that I believe they compete well with the best in the industry but I also think highly of Cotton Cloud as well (see post #34 here) and they would also be well worth considering.
There is more about the most important parts of the “value” of a mattress purchase that can help you make more meaningful comparisons between mattresses in post #13 here.
Phoenix