Sure, I'd be glad to help :)

Because the button doesn't have any forced investment, he only wants to play hands that are profitable from start of hand. Because he's playing vs two ATC ranges, he wants to have value vs those ranges so will be only playing hands in the (generally at loosest) top 50% of hands (though there's some complexity to this number--obviously fold equity helps, position helps, but 3b frequencies hurt, so it's not at all an exact number). Generally button ranges hover in the 30-50% frequencies for most players. If you're playing looser than 50% (or even around that) chances are you're losing money with the bottom of your range ;) I discuss this concept in my Beating Spin and Gos video pack (as well as discussing other spots and the theory behind how wide or tight we should play in each of them).

On top of the general concerns about BU opening ranges, this shallow players understand that they have to call 3bet shoves wide. This generally means that they tend to minraise only hands that can call a shove, and this range ends up being even stronger (and weighted towards big Ax). Essentially, one of the primary reasons they are minraising at this depth is to induce 3-bet shoves and the hands that do well vs 3-bet shoves are Ax and pocket pairs. Sure there will be some wider hands, but these are less common than the strong inducing hands.

Yeah, when in SB in HUSNG you don't need to be as value oriented because when you play a hand it only needs to win the the money you put in (ex 1 SB if you limp, or 1.5BB if you minr) out of a pot that already includes your SB. EX: f your opponent only flats you need to win 37.5% (1.5/4) of the pot and if you limp only 25% (1/4). This leads to us wanting to play many more hands in SB where all we need to be is >-.5bb from start of hand to make VPIP better than open fold compared to in BU where you need to be >0bb from start of hand to be profitable.