ICM Question - Min edge in various situations

[MatteyA28]

So I've been playing around with SNGPT lately reviewing as many of my hands that I can and have been wondering about the min edge needed to make a push/call. The default is .5 but I would think that would go lower if say the blinds get very large (ex. 300/600 in stars sng) or when it gets shorthanded. In HU play shouldn't any +EV play be taken?

So basically...
Should the min edge vary when the blinds get higher?
What about at bubble time, 3 handed or HU?
What should the edge be set at in these situations if it is different from .5?