Love the name, Scamp!! It just conjures up such a happy little guy.
I don't know why he would do the Rabies over the Distemper/Parvo. Glad to see he broke them up. But I'm thinking like you, that the Puppy Distemper/Parvo is given on a schedule, rabies can sort of be whenever. hmmm, hopefully someone else can give some insight. If it was me, I'd call and ask for his reasoning. He shouldn't be offended to explain and if he is, then
that would be a red flag to me.
I usually see a 'new' vet want a fecal, if nothing else, so they'll have a base line to go off of. But it could be that he just got distracted with everything else and forgot to mention it. I'd just bring some poo on your next visit and ask for it to be done.
I'm not fond of Science Diet, but I've found that most vets are. No red flag, truly most vets simply don't have an in depth knowledge about nutrition. It's just not something that they spend a lot of time on in vet school. Just do your own research and decide what's best for you and Scamp. (Did I mention, I love that name!)
Determining the finished weight of these guys is anything but an exact science. It's a rough guess that the 12 week weight doubled will be the adult weight. So if he was 3.5 at 12 wks, you'd sort of think 7 lbs as an adult, but there are so many determining factors that it's really hard to say. That's just one other aspect that's so cool about this breed. Ya just don't know what the adult is going to look like, color, height, weight wise until they are done.