element is just aesthetic, has nothing to do with the weapon's dps.. except cold which has the numbing effect.

Sorry, what I meant was.. the "+254 - 512" is the added dmg.
Just like "+254 min dmg" &"+512 max dmg", it's the same.

The aesthetic part is "+254 - 512 fire dmg". Fire is the element.. which gives the shineeey fiery thingy you see on the weapon. Same goes to holy, poison, lightning etc.

It will also effect how your mobs die.. like fire will leave burning bodies, lightning will have their bodies burst into chunks, arcane gloweee purple stuffs. 
Both produces the same dps (50), so technically, they're identical.

The big 50 dps number shows the total damage per second the weapon will do (includes all the +xxx).
The easiest is to look at the min - max value below the big dps number (50). That has all the calculation done already.

Weapon A can be doing 50 dps with an aspd of 0.95, whereas weapon B doing the same at 1.58. I would definitely choose B in this case. Don't like slow moving stuffs    But they both produces the same output.
Only these:
Weapon damage %
Element damage
Min / max damage
Attack speed

Crit % and Crit damage are not reflected in the DPS of the weapon, but rather part of your character's DPS calculation. Think someone posted the fomula for character's DPS few pages back.