use of ほどには and くらいには in this sentence

Question

context is some bad guys talking to an arrogant rich girl that they kidnapped. Included extra context, not sure if needed.

girl 「調子に乗って……！　こんなの、今だけなんだからね……！　あんたたちみたいなウジ虫は、社会の落伍者は、ろくなこともしないで、みじめな最期を迎えるのよ！」

bad guys 「ずいぶんだねえ、いくら僕らでも多少は傷つくんだよ？　っていうか、それじゃあ君はどんな立派なことをやる予定なんだい？」

girl 「え……？　そ、それは……と、とにかく、すごいことよ！　私、とにかくいっぱい稼いで、あんたたちなんかより上等で立派な大人になるんだから！」

bad guys「どっかのダメ人間みたいなこと言ってるねえ。いつかビッグになってやる、なんてセリフ吐いてる時点で小物だよ」

girl「うるさい！」

人生はバラ色、この先私みたいな美人に挫折も不幸も失敗もありはしないのだ。

そう固く信じて疑わないほどには自信家で、それを許すくらいには、世界は私をちやほやしてくれていたのだ。……今日この時までは。

girl「ウジ虫！　日本人に生まれて家はお金持ち、私はもう、あんたらなんかよりずっと有利なんだからね！」

" from now on, as a beautiful person like me with a rose coloured life, [挫折も不幸も失敗] is not a thing "

To the extent of having "that" conviction without any doubt is a 自信家 (?), as long as this 'extent" is allowed, the world will fawn over me. .... that is until today

1. i'm unsure how to read XXほどにはYYで

2. The concept of [それを許すくらいには] is also lost on me here. Who is doing the 許す here and what is それ? (being a 自信家?)

3. how do ほどには and くらいには differ here?

Another little thing if possible, is 美人に and 日本人に in this excerpt used with the [資格を表す。…として。] definition?

thank you

edit:

after some advice this is my new conclusion:

"(I am a) {自信家 to the extent that (I) believe [この先...]}, because the world, ({それ}を許すくらいに - entire thing as adverb), fawned over me. "

Answer 1

1. 「XXほどに(は)YYだ」 means "to be YY to the extent to do XX", "to be YY enough to do XX".

2. The それ refers to 「そう（=人生はバラ色、この先私みたいな美人に挫折も不幸も失敗もありはしないのだ、と）固く信じて疑わない」こと.

   The subject of the 許す is 世界. 世界 has allowed 私 to believe that 人生はバラ色、この先私みたいな美人に挫折も不幸も失敗もありはしない.

3. ほどには and くらいには have the same meaning here.

---

The 美人に connects to ありはしない.

「私みたいな美人に挫折も不幸も失敗もありはしない」
"For a 美人 like me, there won't be 挫折, 不幸, or 失敗." "To a 美人 like me, 挫折, 不幸, 失敗 won't happen."

日本人に生まれる means "to be born as a Japanese" (≂ 日本人として生まれる). I think the に indicates 結果.

Answer 2

1. You seem to understand this part reasonably well. The ほど indicates the level of そう固く信じて疑わない. Specifically, it's a very high level. The で in には自信家で is the continuative form of だ. The には is something like in order to.

   So, this part says that

in order to believe so firmly without doubting, she is a 自信家.

自信家, by the way, means someone who is very confident in themselves.

2. The それ refers to the previous clause. それを許す then means to allow her to believe so firmly without doubting (such that she's at the level of a 自信家).

   What/who is allowing her to do so?

   The answer is: 世界.

   And how did it allow her to do it? 私をちやほやしてくれていたのだ. You can tell this is the reason because of the ending のだ.

3. ほど here indicates a high level of self confidence. I think くらい here is mostly indicating a contrast with ほど. As in having self confidence can be a good thing, but being pampered is not really so great.