They do not do well in isolation. The metal folding crates are best. Your dog will use it the rest of it's life plus you can fold it up and take your pup with you on vacations. Remember-the crate is a training aid. Pups can not stay in it for extended periods of time.
Slow growth is best.
I do not recommend puppy food. If you use it, change by 4 months of age to a quality adult food. Most grocery store pet food do NOT have adequate nutritional value. Feed according to the pups appearance and weight. It is better to keep a dog on the thin side.