*To learn your new keyboard: For the first few hours, it's best to practice using real words, starting with only the most common letters and adding a few letters at a time. A good resource for this is http://learn.dvorak.nl/ (don't worry about the keyboard picture, just practice the words, repeating each level until you feel you've mastered it).
*The ⌥/altgr plane (qwerty capslock) is important, letting you get punctuation, arrow keys, tab, and return without moving your hands. Keys you rarely use are still available in their qwerty locations (except for ` and ~), but for anything you use frequently (for instance, if you're a programmer), it's really worth it to learn to use altgr.
*The mdash is available by pressing ⌥/ (altgr-slash) twice.
*For Spanish, the ñ and ü characters are available using the acute accent deadkey with n and g respectively. (If you speak Spanish, you know why g makes sense there).