Your questions are broken down into two sections:
What’s too long?
What’s just right?
Is circumference factor? If so, what’s your preference?
In Works of Fiction
How important is the description of the penis?
Would you rather the author merely state there was one present, or give the thingy a courtesy nod and continue on, or give a tasteful account of its dexterity?
BTW, You can thank Emily for 'The Grower'