Hi Bob, welcome to the Luger Forum!
Your 4 point program is okay, except for #1!!!!!!!!!! There are nice 30 Cal Lugers available and you have eliminated a large area of collecting interest. But, if you are interested in shooters, as opposed to collectables, then the 9 mm is best from a cartridge cost consideration.
One point regarding your #2 is that if it isn't all matching, it's not considered collectable.
If you are going for a shooter, I would tend toward the WWII Mauser Lugers, only because the steel alloys were improved between the WWI and WWII pistols. I have both in my shooter cabinet and find them both very adequate.
Good Luck in finding a nice one!!
