Holding the spacebar (before letting go of the mouse button) will change the tool to the hand. Once the hand icon shows, you can either move as is or let go of the mouse button, reposition the cursor, and click-drag to move the image. After you've moved the image (but before releasing the spacebar, release the mouse and reposition the curser, hold the mouse button and release the spacebar.
While using the lasso tool, the option key (alt on windows) will change it to the polygonal lasso too.
Another way to make selections is to use quickmask mode. Check your manual/help for more details.
You best bet is to learn to use the path tool--which can be edited after the fact and then be turned into selections.