Greg,
One does not have to have a doctorate in Greek in order to understand it enough to help his or her bible study. Just a basic understanding of the tenses and a working knowledge of how to look up words in various resources can yield a bountiful crop!
A preacher need not go on and on about what this Greek word means, and what that Greek word means. Most of the time I have dipped into the Greek, it never was mentioned in the sermon. Oh, the fruit from the study was there, in that I had a much better understanding of what the text was saying, and that enabled me to get into the meat of it. But I did not have to stop and explain that I had researched this particular word, which stems from this one, which has a broad meaning of this, and its tense shows us... No need for that, but the knowledge gleened from it helped me in my preperation and delivery by allowing me to be clear and direct, not to mention confident.
Should we learn Greek? If you have the opportunity, yes.
In Christ,
Trotter