Thank you.[W] is dice only. Period. Ever.
+ Attribute will add your attribute bonus, if it appears in the power.
If the power you are using has the Weapon keyword, then you get to add any enhancement bonuses from items, feats, powers, etc. for using that weapon.
Page 276 of the PHB will answer your question. In short, [W] is your weapon damage die only, without any bonuses (which you add in after making whatever multiple rolls), as per Sceadeau's example above.
Correct, [W] is just the weapons base damage die (like 1d8 for longsword).So lets say i have an power i use with my longsword (1d8), 18 str (+4) and some feat that gives me +2 damage...
[W] = 1d8 +2
[W]+Str = 1d8 +6
2[W] = 2d8 +2
2[W]+str = 2d8 +6
And if the longsword becomes an +4
[W] = 1d8 +4
[W]+Str = 1d8 +10
2[W] = 2d8 +4
2[W]+str = 2d8 +10
Correct?
So lets say i have an power i use with my longsword (1d8), 18 str (+4) and some feat that gives me +2 damage...
[W] = 1d8 +2
[W]+Str = 1d8 +6
2[W] = 2d8 +2
2[W]+str = 2d8 +6
And if the longsword becomes an +4
[W] = 1d8 +6
[W]+Str = 1d8 +10
2[W] = 2d8 +6
2[W]+str = 2d8 +10
Correct?
Not quite. I made corrections in red.
+2 from feat and +4 from longsword is equal to +6.
Yes, but if the power has the "weapon" keyword, you get to add "proficiency bonus to attack rolls and damage rolls from your weapon or an enhancement bonus to your attack rolls and damage rolls from magic weapon..." pp. 55-56.