4) Is the overall depth of the memory foam mattress important?

Yes. Although it's important not to confuse the overall depth of the memory foam mattress with the depth of the memory foam layer itself - as it's this, and only this, which will make it feel comfortable, supportive, and overall, deliver the pressure relieving qualities you would expect and deserve from a high quality memory foam mattress. The Ergo Flex™ memory foam mattress comprises a generous 9cm of 3rd generation high-density 85kg/m3 density visco -elastic memory foam, which will provide the quality sleeping experience you would expect for years to come.