We are trying to figure out "budget friendly " options on redoing our bathroom. But I have no idea what this countertop is made of! Anyone know? [ATTACH]79879[/ATTACH]

Hello. i am going to redo a entire bathroom myself, and this is the first time i will be doing it. i have started doing the demo, but removing the cabinet / toilet / tub , and starting on removing the wall/floor tiles with scrapers and pryers. I would like to ask a few things, 1) Is it standard to use 0.5 inches thick cement backer board, and also for dry wall? (i saw an option with 0.375 inch) 2) for cement backer boards - i plan on buying the Durock brand as it comes with 0.5 rather than Hardie's 0.42 inches thick. THe nails selection has a 1.25 inch versus a 1.625 inches Rock-on nails - i bought the 1.25 inches to be used with 0.5inches backer board - is that right? 3) WHen redo-ing the entire flooring - my gut feeling is i should also replace teh old toilet flange but that thing looks very 'strongly' tied onto the floor, so i am not sure if i should consider leaving it alone. In general, do people just replace the toilet flange when they re-tile the bathroom floors? thanks! [COLOR=#ff0000]Moderator note:Combined three threads into one. The timeline may be a little hard to follow. [/COLOR]