Or more accurately, you'll have a greater chance of finding the word starting with a letter that more commonly starts words than other letters. The most common letter is e, but it doesn't start as many words as s or t, so you could start there. Like i said, it's not proven, but i'm hypothesizing that it would reduce the amount of time used to find the word.

I doubt it. If you consider the words to be equiprobable, then the probability for the code to lie in some subset of the dictionary is directly proportional to the size of the subset. So, the probability and the average time increase accordingly and the strategy is of no help.

If the words were not equiprobable, instead, then the most advisable course of action would be choosing them ordered by probability (divided by a cost function if one wants to take length or other parameters into account).