1.) Hopefully it won't; I put it at that wonky angle for a reason specific to the Hemi head. I'll let that one marinate.
2.) Yep.
3.) 20.7mm
4.) Cable. Might just remove it though.
5.) Unfortunately my screen name is derived from a Mustang I had about four Mustangs ago. Now I have a '68 and it's nothing to look at currently. (fun fact: the green car isn't a Mustang.
)
According to Tom Jobe of the "The Surfers," they used straight nitro with only a couple percent of toluene. Toluene desensitizes nitro, but I'm not sure it was really effective at such low concentrations. My suspicion is that it makes the fuel less difficult to light off. He mentioned it in #34, but the whole series is much better than TV.
AFAIK "straight" nitro is still in the neighborhood of 98% purity, but I don't know that for sure. It's information that would have to come from the supplier and they generally don't want to talk to anyone buying less than a train car full of it.