Hello Penny, welcome to BPO and welcome to the wonderful world of Saints! They are the most loving, beautiful, and wonderful dogs ever!
I am going to try and address all of the questions you have posted.
First of all, I want to reassure you that you will be a wonderful puppy-mommy! You say that you are scared that you won't do a good job, but I know that you will do a great job. I know this because you are here asking questions, doing research, and finding out what is best for your dog. You are learning, and as they say, knowing is half the battle
As far as the bowlegged legs go, I am not sure that bowlegging is normal in the front legs, though it is hard to say without seeing it. In the back legs, saints are not bowlegged per-say, but they do have moderatly angulated hocks, which basically means that their feet point slightly outward. If you want I will try and find a picture of zoey that shows what this looks like for youto compare against. Also, HD is deffinately something you should be contientious about. When I got Zoey I knew that HD was something to watch out for, but I did not realize how bad it could get and how soon. Zoey's HD affects her in everything she does and it pains and stresses me to watch her hurting. I have just finished writing up some points about HD for you - I will post them in a seperate post.
It is correct that you should be feeding adult food. This is a preventative measure that you should take to help alleviate HD issues down the road. Adult food will help your pup grow slower, and that is something you aim for with saints. You also want to make sure to use a good high-quality food. If you need help figuring out what foods are good, let me know and I can point you to some articles and recommended food lists...He might have trouble eating it because it is often harder than puppy food; you can solve that by soaking it in warm water for 5-10 minutes or by pouring room temperature water on it and microwaving it for a minute. Also, remember that you need to switch slowly. It is recommended that you replace only a small portion at a time, building up the amount of new food while reducing the amount of old food, over a period of 7-10 days.
It is okay to give treats for good behavior - in fact I encourage it! Food is the best motivator for behavior and potty training! One thing you will probably find is that he will have trouble eating hard cookies - they make bad training treats because it takes forever to eat withpuppy teeth! I reccommend soft treats, like bil-jack liver treats. If you use jerky for treats, use tiny squares of it so they can eat it easily. And make sure you have bully sticks and toys and such for him to chew on - proper chew toys means less chance of him eating up your belongings.
You asked about socialization. With puppies, they learn a lot about how to interact with other dogs and people from their mama and littermates. Generally the litter is not allowed to be seperated until 8-10 weeks, which is how they learn things like bite inhibition. Since your pup was seperated from him mom as a baby and his litter so early, you need to be exra contientious about socializing him. For now, you need to let him meet and have positive experiences with all kinds of people, and with trusted healthy dogs. Once he is fully immunized he can interact with all kinds of animals, but until them you want to only expose him to dogs you know well who you can trust are healthy.
One other thing that I want to make sure you know about is the importance of frequent grooming right now while he is young. You need to make a point to handle him every day. Try to brush him and touch his paws, ears, etc, every single day. It is also important that you make ear cleaning, nail cutting (be very careful not to cut the quick), and bathing regular occurances right now. You want him to grow up used to being groomed and thinking that grooming is a good thing. That way, when he weighs 100+ pounds and have plenty of muscle to fight with, grooming will not be a struggle.
Let us know any questions you have. BPO is happy to help! All we want in return is puppy pictures so we can all drool over how cute he is
Good luck!