How can I stop Android from automatically searching a term when I choose it from my search history?
The anonym with the vague answer is correct, just not nearly complete.  For keyboard-less phones (like my N1), the trackball or trackpad can be used to scroll down the list of suggestions, and that will enter them into the text field for editing.  For most phones with a hardware keyboard like your Droid, use the d-pad next to the keyboard to select the suggestion for editing (some of them still retain a trackball or trackpad).  Once you have the correct entry in the search box, tap it to continue editing.

BTW, I just discovered this, and it's going to make my life a lot easier.