Imo you should always have a moist hide in the viv. Although you will often be able to tell when a Leo is about to shed, I have found that they are not inclined to use a moist hide that has only just been put into the viv - they like things to be familiar to them. I keep my moist hides half on and half off the heat mat area - too cold and they won't use it - too hot and it drys out too quickly and makes the viv humid.
Some ppl like to use a lamp as well as a heatmat but it is not really considered necessary.
Substrate - I always use tiles (or Lino is just as good), some ppl use sand with no problems but I find that it is more difficult to keep clean, needs completely changing after a while, makes a horrible grating sound in the viv glass runners and does carry at least some risk of impaction especially for young Leos.
I have a couple of Tremper albinos (Gertie and Rosie) and they are beautiful.