Hi tor,
You may have seen this but just in case you haven’t … the better options or possibilities I’m aware of in the New York City area are in post #2 here.
Either one could work well for you (you are not in a weight range that 12" of latex would be “necessary” but it still may be a preference). The choice would depend on the specific layering and which one was the best match in terms of PPP. There is more about the effects of thickness in post #14 here.
It’s normally better to have about 2" to spare. Post #2 here and post #29 here may also be helpful.
The Surround Ewe doesn’t list any specifics on their site and I don’t have any knowledge about it so I really don’t know.
Again … these are the types of questions that only your own experience can know. It would be typical for wool to compress about 30% over time and some compression in wool doesn’t normally affect alignment although it can gradually reduce comfort over a longer period of time as the wool compresses and packs down. I don’t know when you would cross the threshold between when a wool mattress topper is comfortable for you to when it would start to become uncomfortable. I think that a minimum of 5 years would probably be realistic but many people keep their wool toppers and are happy with them for much longer than this.
It would make some difference yes but I don’t know how to quantify how much because there are so many factors involved with sleeping temperature (see post #2 here) and it will also depend on where they are in the oven to iceberg range. The wool wouldn’t be thick enough that compression would cause an issue and most of the pressure relief would come from the foam layers in the quilting and the mattress not the wool.
It wouldn’t be necessary under a slatted foundation or platform which already allowed good airflow.
This would be a preference choice not a “better/worse” choice. Dunlop and Talalay can both work well in comfort and support layers in a suitable design and firmness level. There is more in post #7 here about the difference in “feel” between them but your own experience would be the most reliable way to know which one would be “better for you”.
There are too may unknowns, variables, and personal preferences involved to use specs (either yours or a mattress) or theory at a distance to predict what you will do best with (see mattress firmness/comfort levels in post #2 here) so my answer here is just as you may have expected … the manufacturers themselves are always the best source of knowledge and guidance about their own mattresses designs and options 
Phoenix