Welcome to YT.
Food, you should feed your pup whatever the breeder was feeding. If you decide to get better quality food, there are some very informative stickies/posts on high end foods. Just remember you have to change the food slowly. ex. 1/4 of new + 3/4 of current
Potty.. I think most people prefer crate training. If you do a search on potty train, you'll find a lot of posts on different methods, issues that arose, etc. Please always keep in mind that some pups take longer to be trained so be patient.
I use disposable pee pads. I trained both Magnus/Zoey on pee pads from the start b/c of certain circumstances. But now, Magnus holds till I take him out and Zoey's the only one that uses the pads during the day. She's only 5.5 lbs so she can't hold it as long. Also, I think she just feels safer inside while doing her business.
The grass pad.. I think it's a hit or miss. Just like regular pee pads.
Any other advice?.. Lots of patience. And of course, make sure you're keeping up with the health maintenance such as heartworm meds. Make sure you know what food can be poisonous to your pup in your home. Ex. chocolate, oinions, etc.. Keep nutri-cal or something similar in your home along with some other things.. it'll be something like a first aid kit for pups including a emergency vet contact number.
Try not to take the pup out for walks till after about 1 month (or was it 3 months? someone please correct me if I'm wrong) s/he had the first set of vaccines. The pup will be very vulnerable to disease. I think if you keep him/her in your own yard where you know it's clean, that should be fine.
Never leave your pup unattended outside. I don't know what area you live in but if there are hawks, foxes, etc. your pup will be in danger. Even if you don't have these type of predictors, you still have human proprietors that can dognap your pup.
Never get just a collar/leash for walks. Buddy belts are pretty popular (I believe another member Maximo sells them) and is very favored among small breed owners.
Sorry it's so long... I'm trying to keep mind off something else...