Whenever I'm pushing for gains.
Monohydrate, the creapure kind.
Usage lasts for however long I'm pushing for gains, which for me is usually 6-8 weeks before I have to back-cycle weights. With that said, there's no NEED to cycle creatine.
I load the first couple days, 20g/day, then 5g from there on out. This isn't required, but I personally don't see the need to lengthen the saturation process outside of personal reasons (stomach issues and whatnot). Would rather get in more quality gym sessions.