Wish I could answer your questions on that. Spill timing is something I have only heard and read about but never had to do it. Maybe do a search here as it has been explained in th epast in simple terms with good outcomes.
Never tried to understand the internals of an injector, just free them up to make them work, sorry.
Soon enough someone with a lot more knowledge than I have will offer help. So get stuck into the fuel delivery system while a proper answer can be supplied.