A) a Demology or Afflication warlock and keep up the 5% crit far better then a fire mage via Imp Shadow Bolt. So attempting to refresh scorch in between there shadow bolts is a huge dps gimp.
B) Not that I know of. But here is a handy addon that will track all mage procs, and debuffs. It also comes with a stat monitor so you can make sure the 5% crit is being given... by somebody.