The best 100% natural latex mattress to suit our requirements?

Hi there - Very impressed with your highly informative website and FAQ section in particular.Based on our parameters below, can you please advise us which mattress from your range you would recommend.1. I weigh 106 kg, my wife weighs exactly half that. Consequently we are considering whether we should go for one mattress or whether the 'zip and link' solution of two singles would be better.2. Our existing bed that we intend to keep has wooden slatted base under tension (There are two sets of slats, one set on each side of the bed ie one set on my side and one set on my wife's side. They are 'under tension' in so far as they are slightly arched in the middle and need bending to slot into place.)3. We need a mattress that is 200 x 160 which i understand is not a standard size. Can you confirm and let us know if you do custom-made sizes at these dimensions? Will this affect the 30 day 'love it or return it' guarantee?4. We had a fantastic experience with a Dunlopillo mattress bought 15 years ago which was a single block of talalay 100% Natural Latex and consequently want to find that quality again. We have excluded buying from Dunlopillo a second time as our research shows that the company has changed hands several times and they are opaque re the whole 'latex/pure latex/natural latex' make-up of their mattresses.5. My wife is concerned about fire-resistant materials and we have read your posts here on this. I understand you use a 1cm layer of graphite latex on top and bottom of the mattress. Is this graphite latex '100% natural latex'? What chemicals are in it to make it FR? We have seen an eco mattress company based in Manchester (www.dojoeco.co.uk) who say they use 'wool as a natural fire retardant layer without the use of fire-retardant chemicals so that our mattresses pass British standards for fire safety'. What is your view on this?6. Our budget can stretch to the top of your price range. We figure that we spend approximately one third of our lives on our beds and so it is worth investing in a good one.