First, Welcome to the TDR! Glad to have ya!
The engine wont ever get too hot, its an approx 800watt heater, and should be used below 40F outside temps. The truck runs at 200F usually, the block heater would never get it that hot.
I put mine on a 20a grounded timer, and have it turn on 2-3 hours before I leave for work. If the temps get below 0, I bump it up to 4-5 hours.
Speaking of block heaters, I just noticed that my window sticker doesnt include a block heater, but the heater+cord is already installed. I was going to just buy the cordset at genos, but this is a nice surprise...
-j