Hi Keith,
Welcome to the hobby. Please check out the web site linked below. The site was compiled by another new collector, Will Knight. It has a wealth of info for beginners.
A short answer to your questions.
The best place to buy chips is at the casino for face value. There are also many collectors that sell chips. I'm sure many will post a response here or send you an email.
Trading chips is a big part of the hobby. Get extra chips at any casino you visit. Offer to trade those chips to other collectors for chips you need. Trading for current chips is usually at face value with each party covering the mailing costs.
There are many catalogs / guides on chips that cover most of the specialties / areas. Decide what you want to collect and buy the book.
Paul