Yu-Gi-Oh cards and decks question?

Right, so I've been out of Yu-Gi-Oh for a long time, like, reeeaaally long. But recently my friend started back, and got me interested again. The first thing I see when i go into Walmart is all these new packs, giant tins and monsters I've never even heard of before. I've recently purchased a few of these packs, but I want some detailed information. For starters:

1.) Do any of these new packs have any of the older cards in them? Of course I mean ones such as Dark Magician, Blue Eyes, etc..

2.) I've heard they make retro packs as well featuring many of the best older cards, what is up with these and where can I find them?

3.) Lastly, what are the best newer packs? I purchased the Onslaught of the Fire Kings, and some Hidden Arsenal 7 packs as well as some generic packs.

4.) I lied, this is the last one. What are the best locations to buy cards at? I'd hate to buy them online, just to wait a whole week to get them in and be disappointed. I'd rather be slightly disappointed right that very second. Anyway, thanks for whatever help I can get.