Bit of a yes to most of your questions, and add "the right fresh bean (for your taste)" to the list, like maybe Espresso Wow from beanbay, or even a bag from your favourite cafe.* But IMO, a ristretto could be done on any basket. (edit:* and by "any", I dont mean a single, although Im sure some of the snobs here can make a pretty mean ristretto with that, too).
Have a look at the home-barista site for excellent tutorials like "Espresso 101" and " Barista Technique: Good Extraction, Good Espresso".* Theres a pretty nifty graph there if youre into the techie side of stuff.
Hope this helps.