In response to your first question, it would be 1 - 7%, not 2 - 7%, a similar concept to LPK and such.
Depending on the weapon you use, dexterity and strength affect your damage differently.
For more information on that check here :
http://ladderslasher.d2jsp.org/index.php?g=3To answer your algebraic question, I would presume it's this formula : str muliplier * dex multiplier * ee * base dmg = real dmg
just factoring in the percentages from the above link.
Hope this helped!
Let me know if you have any more questions.