Chronological change log for Cox Pee Wee 020

First questions.

Perhaps one of the easier things to gauge would be the dates of the various packagings of the engines. The blue card backed blister pack for instance, I presume, was first in February 1957 and then eventually we wind our way to the very corporate looking black and red fold out boxes toward the end of the line. Looking for dates here, but I may need to supply pictures so we can all be sure we're talking about the same packaging.

When did Cox stop putting the scalloped taper on the front of the 020 crank case? In other words when did they stop doing the so called 'swan neck' Pee Wee and make that part straight instead.

When did they introduce the starter spring? From pictures it seems the starter spring was introduced at the same time as the swan neck was abandoned but I'm looking for dates here.

My own examples of the Pee Wee range from a Pinkish Purple in anodizing through to a good solid red and even completely silver. Is this any help in dating an engine and if so, can you help with the dates of colour introductions?

When did they stop engraving the words 'Thimble Drome' on the fuel tanks of these engines?

Did the back plates of these engines always come with the fine wire mesh circular air filter or did some not? I've seen numerous back plates where there is no wire mesh and have always wondered if they shipped like that or had someone removed it.

When did they introduce the back plate with just the single filler tube? MH Aero's website seems to indicate this change came in with the RC version but it doesn't seem that it needs to be specific to the RC version for any reason so I'm wondering if all the Pee Wees came like that from then on.

That's it so far. Plenty more questions to be asked and answered of course. Any recommendations for a good book?