Re reverse in HI idle: The manual for the B200 I fly specifies HI idle for short landings due to the faster response to get to significant reverse thrust. That's because the engine will already be at 72% power when reverse is selected and then increase power from there. From LO idle the engine must accelerate from 52% when reverse is selected. Obviously there's a period of time needed to get from 52% to 72% before the LO idle scenario can match the result from starting when already at HI idle.
I don't usually land with HI idle, even on short-ish runways. I find the aeroplane tends to float more. I prefer to leave it at 62%* then, during the flare or immediately on touch down set HI idle, max RPM** and then select reverse. The spool up time from 62% isn't as bad as from 52%, of course, so by the time I'm ready to select reverse the engine has already spooled up to HI idle.
*left there from before take-off to keep the aircon running on the ground
** Usually left at cruise RPM until touchdown unless a very short runway or turbulent/gusty conditions that will require quick response times - in which case I'll use 72% idle - or lots of icing.