From: Halifax, Canada
the early factories make no difference - it doesn't start producing until the aircraft is availible anyways so it doesn't hurt.
i will let you do stats for everything you would like to see included and then we will discuss later which we should generalize because of low total production, etc. for example the Hs 129, which although had a million varients, really had a short and low production run so we should perhaps have just 1 version of it in production for a year to keep it simpler for everybody else and make it easier to fill a couple wings of the type in game. the final version would be an average of all the main varients stats, or perhaps the stats taken from the best version. on the other hand i am looking forward to the Fw 190 series being broken down more, as 1 version in production for 3 years is a little silly as it was continually upgraded! i guess in general cheap aircraft should be an absolute minimum of 6 months in production, and preferably minimum 9 months to make it easy to equip the wings. too much aircraft upgrading really hurts pilot experience in the game!!
i must admit, the He 177 worries me a little as it is so much better than everything i don't know if it can be expensive enough!
i'll see if i can find some more info for ya in regards to sov aircraft - i'v, um, downloaded a ton of aircraft books so if you are looking for anything specific let me know and i'll email it to ya if you'd like.