I think an obedience class would be wonderful for you two.
I never took one, as I trained Jackson by myself, but I still want to take one just for the socialization and extra training. It seems like it'd be fun.
A good thing to teach is 'focus' or 'watch me'. I've found clicker training to be a wonderful method, as a clicker is more consistent, human voice is not. But using the same phrase like 'yes!' when they do the correct thing works just as well. Go to youtube.com and search for users 'kikopup' and 'zakgeorge21' You can learn quite a bit from them (I know I have). I find training to be so fun and it really forms a bond between you and your dog. Jackson knows over 30 tricks now and all we done with just us two having fun. It's usually only 10-15 minutes a night out of our day. He really LOVES performing his tricks, and that's why I do it, because it occupies his mind, he enjoys it, and will even come over to me at night (when I'm usually on the computer) and start whining at my feet and when he sees the clicker he gets all excited. Once he becomes bored with it, we stop, and end training sessions on a good note.
As for your pups size,
nothing is a guarantee, and no breeder should ever guarantee a size. Jackson was 6lbs at 12 weeks old, 8.6lbs at 16 weeks old, and by 6 months he was around 12lbs. He continued to grow past 1 year of age and is now almost 16lbs lol.
He's a perfect size for me though and I wouldn't want him any other way.
The best advice I can give you is make everything FUN!
If the pup doesn't wanna do it, it's because they're not enjoying themselves. The human should be calm, patient, and not get frustrated or angry, being calm yourself really reflects on your dog as they feed off our energy, since they do not speak English, energy is huge!
Good luck with everything!