Right now from what I can see it takes 3 votes to get to the homepage (I checked using the Swequity link, it was at 2 and not on the homepage, after one more upvote it was), but those 3 upvotes have to be in a fairly limited timeframe to be effective. 3 points in 5 hours doesn't cut it, but 3 votes in a half hour or so is enough.
How long it will stay there depends on how many votes and flags it gets after that.
How long it will stay there depends on how many votes and flags it gets after that.
A flag counts as multiple downvotes.