Hypoxia

It is a dilutor demand mask so, if the cabin is pressurized, you'll use almost no O2. Dilutor means the pilot only gets the O2 required by the existing partial pressure available, demand means you only get it when you inhale. You must be in NORMAL , not 100%.

TCDS says....minimum crew is 2, so entirely legal to log the time, whether or not the captain has a SP waiver. SIC T/R is required outside the US, but not in the US.

GF