Q:
Engineer Dungeon + Farm question.
Guild Wars 2 plays differently than other MMOs. Specifically, there are no dedicated healer or tank classes. Thus, in dungeons especially, everyone is responsible to look after her/himself. And of course you can, because every class has heals and defensive skills.
That being said, if you want to be competitive in PvE dungeons or in sPvP, then you absolutely cannot play a glass cannon build. Your typical MMO-player intuition of trying to work out all the bonuses to your damage and your crits won’t cut it in Guild Wars 2.
I don’t want to give you specific things to do or build, it’s the fun of this game that you can experiment around and try lot’s of things. Don’t let anyone fool you into thinking that there is only one viable build (for any class). However make sure to have a balanced build, use runes / craft armor that will also give you toughness or vitality. In PvE dungeons and sPvP that additional toughness will mean the difference between being one-shot and being able to survive a bit and counter however you see fit. This will make it much less likely that you and your party are wiped in dungeons.
So in a nutshell: Guild Wars 2 doesn’t reward player specialization. Instead try to make a balanced build keeping survivability in mind.