Re: Are all DLC`s included in the Mass effect trilogy package?

@ZAKITASHI No not all, and it depends on your platform which DLCs you get.

I assume you are on a PC because you linked that page, so you get all DLCs for ME1, as you already know and the Online Pass for ME3.

For ME2 it's a little complicated. You get the "Cerberus Network" that gives you access to  "Normandy Crash Site", "Cerberus Weapon and Armor", "Arc Projector" and "Firewalker Pack" 

"Zaeed — The Price of Revenge" was also available through the  "Cerberus Network" but there was a little confusion lately, so I am not sure if that is still the case. 

Edit: Of course you also get the free MP DLCs and the free "extended cut" for ME3