Wow...that is a LONG list of questions...and we are in the midst of deciding how soon to spay Pua...wow...I'll be watching for answers!
On your issues (spay wise) I have not yet seen any long term health reports confirming any of this with regard to age of spay / neuter. There are risks every day. The genetics of where you got your dog, what you are feeding it, as well as heath care that can determine the risks you are naming. Spay IMO when done by an experience vet, does not affect long term health (again IMO).Does spaying put my puppy at higher risk for these nasty cancers, vaccine reactions, thryroid issues, and urinary issues and do these risks outweigh the benefits ie- mammary cancer prevention, her girly figure, and convience for me?