Welcome to The Daily Puppy Jai and Biffy, and Jai's gf, from Oliver & Henry, and their Mum, in London, Ontario (Canada).
May I suggest you check out two different sections in our Forums for your questions. The first one being the Behaviour and Training Section. If you do not see an existing thread that pertains to your walking question, then by all means start a new one. I think most members would encourage you to enroll in puppy training classes for a start.
The second thread would be the Health Section where we discuss feeding, and other health related topics. The short answer to your question about puppy food is that it is generally given for the first year of life. Most would advise that you stay away from "wet food" and find a good quality kibble, unless of course, you wish to raw feed or do both.
Keep in mind that my above statements are very, very broad, and even I could debate my own comments, so it really does require a proper discussion to find out about your lifestyle, where you live and what's available to you, etc.