RE: Glow Plug Idle Bar
That sounds about right. I've only heard that the idle bar was there to help keep the fuel from cooling the element when you throttle down. I have never heard about the history of it though.
I've been flying for about 15 years and here's what works for me. In all of my two-strokes I use the OS #8. In my four-strokes I use the OS type F. I also keep a couple K&B long idle bar plugs because I sometimes encounter an engine that seems to run better with that. Often students will come out to the field with some unknown plug in their engine. Sometimes it will work fine, sometimes not. I remember fighting with one guy's engine for an hour trying to get it running right. Finally we put a K&B idle bar plug in and it ran fine.
99% of the time engine problems are due to one (or more) of three things:
1. Engine is out of adjustment (high and/or low end needle).
2. Bad fuel.
3. Bad glowplug.
That's my 2 cents worth...