If your dog starts marking, I vote get him neutered... Different dogs start marking at different ages, depending on their environment and what they learn (like if they get to watch other boy dogs lifting their leg to mark). I have a friend (not a YT member) who has a 3mo dog who marks EVERYWHERE - what a freaking nightmare... but my pup got neutered at 6mo and has never once lifted a leg to mark, or pee for that matter either. He's a girly squatter :-) and we're fine with that. In my opinion, you should neuter your dog as soon as the vet says it's safe, as early as possible.
Part of when a dog starts marking is genetic, and part of it is learned behavior. Either way, it will happen sometime probably between 3 months old and 9 months old, from what I have read and seen. Unless of course, you get him neutered quickly enough. My uncle has three boy dogs who were all neutered before six months old, and the rest of my (uneducated) family makes fun of him because all three boy dogs always squat to pee. But I think it's awesome because he neutered them in time and never had to worry about controlling marking behavior. :-)

Not marking is without a doubt a good thing! So be sure to neuter as soon as you safely can. My vet's safety cut-off is 5lbs and 100% healthy, including a blood test.
Lauren & Nikko
PS: I forgot to mention the teeth bit... the way I see it, the worst case scenario is that they haven't gotten enough new teeth in yet to chew solid foods without their baby teeth. If that's the case, then they can eat canned food for awhile IMO. :-) It shouldn't take all that long to get grown-up teeth.