Bubble questions.....

Fairly common scenario with 4 left and blinds 75/150:

Player #1: 4000 chips

Player #2: 1500

Player #3: 800

Player #4: 1700

in that order.

I'm wondering about the strategy here.

Pretty sure that #1, #2 and #3 should be pushing any time it gets folded to them in the SB (with any 2 cards). #4 is kinda screwed here, since he doesn't want to be pushing into the big stack without quality cards.

Should #2 be pushing on the Button a lot?

Should the medium stacks be tighter than normal waiting for shortie to bust out?

What about calling standards for the medium stacks? Should they avoid calling all ins from anyone but shortie without really premium hands? What about small pocket pairs?

I was #2 recently and pushed on the button with A6o. #4 called with QJo.

I think the call was truly stupid, as he had a marginal hand and was setting himself up to get shortstacked.

What about my push? Should I have been tighter with the shortstack needing to make a move soon?

Thanks