We already know that Vanquish is hitting Japan on October 21st, but a day after, everyone in Europe will have the pleasure of getting the game. The three weapon pack will be for pre-order customers as well, only in Europe it will be selected retailers.
The DLC for pre-orders are the same as the Japanese release. That means Boost Machine Gun, Laser Canon and Anti Armor Pistol. If trend goes like the Japanese release, the pre-order DLC will be up for sale after the game comes out.
[UPDATE:] North American release date for Vanquish announced, October 19th. Take that Europe and Japan, last to be announced and first to come out. [/UPDATE]