Hi,
1. The writer has been describing an argument between her friend and her friend's husband about her friend's husband's table manners.
あれはどうやって解決したのか気になったので聞いてみ た。すると、あれから彼に自分の思いを伝えたら、食べ 物を粗末にしてはいけないことを理解してくれて、それ 以来たいていは残さずに食べてくれるようになったとい う。
My translation: "I wondered how the matter had been resolved, so I asked her. She said that she had explained her feelings to him (= her husband), and he had understood that bad table manners were not allowed, and since then had usually not left anything uneaten."
Assuming this is is essentially correct:
a) In あれは, does あれ refer to the argument described earlier?
b) Does あれから mean because of the argument described earlier?
2. 以前は石頭だと決めつけていたのだが、最近は「なかな か頑固なところがあるな」と、むしろ感心することもあ る。
Out of this I get "Previously I had made up my mind that he was pig-headed, but recently I've more admired ..."
a) Does ところ refer to aspects of the other person's character?
b) What does なかなか signify here?
c) Is 頑固なところがある more favourable to the other person than 石頭だ?
3. The topic is burning or burying rubbish and hoping/wishing we could then forget about it:
それっきり忘れられたら良かったのかもしれないのだが ・・・。
Is 忘れられたら potential ("if we could forget the rubbish") or passive ("if the rubbish was forgotten")?
4. 大量生産、大量消費、そして大量のゴミという社会の仕 組みを反省し、可燃、不燃を問わず、とにかくゴミの量 を減らさなければと考えた。
My translation: "Contemplating this society organised around mass production, mass consumption and mass waste, (people) concluded that somehow the quantity of rubbish, whether flammable or non-flammable, must be reduced."
Presumably 減らさなければと考えた means 減らさなければならないと考えた, yes?