～が言うには　・　だけは　・　仮にも　・　のでは

Hello,

Could you help me understand these sentences as well, please?

1)妹さんが言うにはばーぶちゃんが亡くなった日から毎晩どこかに出かけてるって聞いたんだけどぉ～
ばーぶ is the name of cat
As I understand it, this sentence means "According to what your sister said, I heard that since the day Babu died, you go somewhere every night.". So ~が言うには means "according to..." ?
Is there any grammatical explanation for this? For example, is には replaceable with 時 here?

2)お嬢だけあって変にプライドだけは高いのなー・・・
This is not the first time I encounter だけは, but I want to confirm my understanding.
Here, it doesn't mean のみ, but "at least", right? ("As expected of a lady, at least when it comes to your pride, it is strangely high...")

3) 生き返る薬を作って 亡くなったばーぶちゃんに飲ませるとか・・・何考えてんの！？しかもアンタ仮にもお寺の息子だってのに・・・
There is an entry in the dictionary for 仮にも but it doesn't seem to fit this sentence. And the も for the dictionary one seems to mean "even".
So, in my sentence, does も mean "too/also"?

4) The sentences have no connection.
1.姉上・・・こんなすぐに帰らなくてもいいのでは・・・ずっと道場にいてくれていいのに・・・
2. おそらく降谷(ふるや）という*some school name*の男子生徒と一緒におられるのではと・・・
In the second sentence, a butler is reporting to his master about his daughter.
a) Does のでは = のだ?
b) Does the のじゃ that I hear some old people say, come from this のでは?

1)
～が言うには can be replaced with ～が言うところによると. This expression is from classical Japanese and therefore any nominalizer would not be used after 言う. に indicates a ground/basis of the clause following it.

2)
It seems to imply 何もできないのにプライドだけ高い to me.

3)
The definition #2 "十分でないにせよ、一応ある事実があることを表す。曲がりなりにも。かりそめにも。「―宣言したのであるならば実行すべきである」" is the meaning of this にも. It's the same as ～にしても.

4) a)
ない（です）か is omitted after のでは.

b)
Not really. じゃ is a dialect of だ.
こっちに来るんじゃ ＝ こっちに来るんだ(not こっちに来るのでは)

1) Thank you! I can't say I understand it though. Classical Japanese is a black box, that I don't plan to open soon. Not while I am not even able to comprehend half of common Japanese. Basically, if you ever want me to stop asking questions about a certain matter, you can just say that it is related to classical Japanese. (no, please don't do that)

2) Ahh, It makes a lot more sense now.

3) So, does 仮にも = "even if it is temporarily" >>> "Furthermore, even if it is temporarily, you are living at a temple....(and you did that?)"
It's not really what I would expect her to say, and I'm not sure I get what she implies by "even if it is temporarily". Although I might be exaggerating it, but maybe something like: "しかも、あなたは今寺の息子だよ。ここから移ってからこんなことしても知らないけど、ここにいるうちにそういったことしてはいけない。"

4) a) Thank you! Is のでは related in any way to politeness or refined speech? or is it just a coincidence that in both sentences the speakers happen to come from a traditional family.

3)
This 仮 doesn't refer to conditional. 仮にも is more close to "though not quite satisfactorily" here.

4) a)
The latter. んじゃ would be more common in casual speech, though.
e.g.
お姉ちゃん…こんなすぐに帰らなくてもいいんじゃ…ずっと道場にいてくれていいのに…
多分降谷(ふるや）という*some school name*の男子生徒と一緒にいるんじゃ、と
(Hmm, いいんじゃない？ / いるんじゃないかと sounds more natural to me. ない might be hardly omitted after ～んじゃ, comparing to ～のでは.)

3) Something like "Although living at a temple is not a good enough reason not to do this, you should still consider it"?

Something like although you might not be good enough as a son of a monk, it is a real fact that you are a son of a monk anyway.

Ahh, that didn't even cross my mind. Thank you, Toritoribe!