.5" Preheats on my machine in apx 22 seconds, however I have High preheat setting That I control through a homemade box using solenoid valves & flow tubes to regulate post preheat flame to a manageable level. Also, I am using Propane/Oxygen. 1" steel preheat is 27 seconds with the high preheat. Without it more like 1 1/2 min.
Small holes, Yes, I run a much higher feed rate Probably double.