1. That's up to you. Smash brewing is 1 base malt and 1 hop....the decisions after that fact are up to you. If you're trying to learn about hop flavors, I suggest using a basic two-row malt for all of your recipes. Then, each new batch, add a different hop.
2. Anything listedf as a base malt will have plenty of enzymes to work for you. I've used munich as a base malt and it works fine. You've probably heard that munich has to be mashed...
3. Again, the hop choice it all up to you. I prefer to stick with lower AA hops that are used for flavoring. But some, such as Centenial and Nugget are also good in my opinion. No, there's no such thing as neutral hops...not that I know of.
4. You should be aiming for a beer with the specs of a pale ale. This isn't written anywhere, it's just what I've done. I usually do around 4% ABV and 30-50 IBUs...it's all personal preference. SMaSH really isn't a style of beer, so nothing is set in stone.
5. 2 oz of hops is plenty for a basic recipe. With just a base malt, you're not letting anything get in the way other than the one malt flavor.
6. Adding anything other than 1 grain and 1 hop would make the SMaSH null and void.
7. If you really want to get into designing your own recipes...I highly suggest picking up Designing Great Beers. It's a great book and I still use it every now and then. It may seem very advanced at first, but read through it for awhile and you'll be making beers to style in no time. It also has a lot of history on each style too, which is nice.
8. This isn't necessarilly the purpose of a SMaSH, but it's not a bad place to start. If you really want to know how each hop tastes, I suggest making a basic pale ale recipe. 8-10lbs of base malt, a little crystal malt, and one bittering hop addition. The bittering hop doesn't matter much as it doesn't add a whole lot to the flavor. You'll want to then split the batch into 5 or 6 - 1 gallon jugs and dry hop each with a different hop. This will give you the best flavor sample of the hops your using.
Hopefully that covers all of your questions...
You will eventually get an idea of what you like and what you don't. You'll also get to the point where you can pick certain malts out without seeing the recipe. Hops are a bit trickier. I'm still only able to pick out certain hop flavors...cascade, centennial, nugget, chinook, simcoe, amarillo, tetnanger (sp?), northern brewer, saaz, and maybe one or two more. These are about the only hops I use anyway...