We are pretty much novices at mattresses, but have learned lesson about overall mattress heights when combined with box spring and bed frame rails. Never gave overall height the thought we should have... big mistake as the plusher, pillow top mattresses can be quite thick. Having a shorter wife, I've learned some lessons
Last purchase went with low profile box spring and removed the castor/wheels from the bed frame to achieve a comfortable access height for her. Also noticed between our two houses, the edge firmness on the mattress in Florida is "stiffer" which make rolling out of bed easier than the mattress in Indiana that sort of sinks on the edge on exit.
I, too, wonder about the disposal question. Looking forward to comments.