This is a very simple question for 2 reasons:
1. The #1 rule in life is NEVER press the big red button.
2. It do not have the RIGHT to decide who goes to heaven/hell.
What if I tore someone going to hell away from someone going to heaven because they didn't have the time to change? That would all be on my shoulders whether I know it or not.

So by not hitting the button I would be allowing people to continue living their lives whether the question is the first one and life is pointless, or the second one in which there is an afterlife.

In the first scenario I wouldn't be able to do it. I like life too much. I've worked too hard for life to ruin it for everyone, especially myself.

The second scenario though I would press it ONLY because everyone would go where they belong. My only hope would be that I get to go to Heaven to escape the cactus monster that's lodged in my ass.

I would most definitely not press the big red button. There is no point to it. If the button destroyed all humans, but left the Earth in tact, then I would for certain. But Earth is what I care about, destroying it would accomplish nothing. And, of course, it is in fact "boring". I've discovered recently that the world is a lot more interesting than I originally thought, in the good and the bad. Sure, it's not perfect, but
*drum roll please*
it's better than nothing. Haha, see what I did there? But why do I have the right to nullify everything, just because I want to? The eternal "what would've happened if I pressed it" would stay with me for the rest of my life (which in the history of planet Earth, is microscopic). But of course, words are pretty easy, actions are harder. The temptation would certainly be there, and I'm not sure I'm a strong enough person to avoid it. So I guess my answer is actually a "maybe" sort of deal

As for the second question, I'm not really sure. Religion always messes things up for me. I guess I would, since we're all apparently ending up in our appropriate places in the end. But I'd feel guilty, because what if the people who went to Hell could have redeemed themselves? I didn't give them the chance.