Based on those numbers you should probably start with the 16 kg (36 lb.) KB and move up from there. You'll always have use for a lighter KB in the future. Start with one to see if you like it - you may decide you hate KBs and that's fine.
After that you have many options in terms of cast KBs, adjustable KBs, and so forth. I actually prefer doing clean and jerks with 2 KBs as opposed to a barbell. I currently own 6 KBs (5 "adult" ones and one is a little 10 pounder I bought for my kid) and 1 Kettlestack handle - a very good product.
As far as instruction, I don't think the book does the best job of showing the technique for the snatch. I was lucky in that I had taught myself the Olympic lifts and was able to apply that knowledge to KBs. I then met up with some local KBers who taught me how not to bang up my forearm on the snatch. So, I never needed the DVD to learn the technique, but that might be your best option. I've never seen the DVD so I can't comment on its quality. It's not that the technique is hard to learn - if you can power clean you already know about 90% of what you need to clean and snatch a KB - but it's important to learn to not bang up your forearms. Once you're able to do high rep snatches with the 70 lb KB, this will become really important. They're lots of fun and addictive.
For some really inexpensive KBs try Everything Track and Field - about half the price of Dragon Door.