Forget about the Smart Tool (multi-tool), and forget about clicking the on-screen tool icons. Use the function keys F6 to F8 to choose the active tool. Using this method you'll only need the Selector tool ('I' beam) and the Grabber (hand): all other edits can be achieved using a combination of one of these tools and keyboard shortcuts. The Grabber is used for moving audio and MIDI regions around. Stick to the 'Object' variant of the Grabber, as the 'Time' Grabber is more limited. The Selector can be used for everything else. Trimming is achieved by dropping the cursor at the desired in or out point and using 'A' or 'S' on the keyboard to trim from or to this point. If you need to audition the region before trimming, you don't need the Scrub-trimmer tool. Instead, you can hold down the Ctrl key, which turns the Selector into the Scrub tool, enabling you to find the right spot to drop the cursor. Adding fades is similar: place the cursor at the point you want the fade to start or end, then use the 'D' key to create a fade-in, or the 'G' key for a fade-out. Crossfades are created by selecting across a region boundary and pressing the 'F' key. The fade will start and end at the extremities of your selection. You won't need the Zoomer tool very often, because you can use the 'R' and 'T' keys for zooming the display in and out horizontally. Zooming centres the screen on the current cursor position. If there is a selection on screen the zoom will centre on the start point of this selection. Use the left and right cursor keys to switch the display between the start and end of the selection.
The number one key command in Pro Tools is Command+'=' (Start+'=') which toggles between the Mixer and the Edit Windows. Even if you have two screens this can be useful, because all the single-key edit commands are suspended if the Edit Window is not the active window.