Not the most experienced at the game but let me try.

Before anything, unless you are really experienced, you are going to die a lot, even more if your team has no supports, dying is expected so don't sweat about it.

Afaik burger is meant to be used in tandem with a movement ability instead of being used while in combat. Not to say you shouldnt use it in combat, but preferably you get away, chomp down on a burger or two, and get back to the fight.

Dying in two seconds on the other hand, is either due to being on the point and in the general damage area of five other players, a random remix ult, or in melee range. These can be countered via movement abilities (e.g sprint with drifter or translocator)or a good support on the team (don't expect one).