のう / 吹き鳴らす / 見てらっしゃい / 後

Hi,

1. 「それがのう、わしはもう、新しい「占い学」教師を見つけておる」

Is のう = の? What does それがの(う) mean?

2.「ラッパ水仙を持ってね・・・スプラウト先生が育てているラッパを吹き鳴らすやつじゃなくて・・・」

What does 吹き鳴らす mean?

3.「まあ、見てらっしゃい」

I assume らっしゃい = いらっしゃい. This is in an informal chat between two school pupils, so why would such a formal word be used?

4. 朝食の後、・・・

後 has the furigana のち. I wonder why, since it is a simple character (albeit I am often unsure how it is pronounced in any given context, but I assume native readers would have no such problem). Are there multiple ways to pronounce 後 here? What is the difference?

2. Just what the characters would indicate.... to cause to sound by blowing. It's talking about playing a ラッパ.

3 & 4 somewhat formal/archaic speech. You're reading Harry Potter; its loaded with this sort of stuff, isn't it?

見てらっしゃい
見て(い)なさい
見て(い)ろ

Sometimes the reading isn't always clear even to all native speakers, hence the presence of the furigana.

1)
の（う） is a sentence final particle (well, it should be called "clause final", though); old people's dialect version of ね（え）.

2)
の in the above is exactly the same function as this ね.

As Mike-san explained, it's 吹いて鳴らす.
e.g.
太鼓を打ち鳴らす
ギターを弾き鳴らす

3)
It's more likely "refined", rather than "formal". The speaker is a girl, right?

4)
The meaning is the same, but another possible reading あと sounds more colloquial.

Thank you both, I was reading (2) as ラッパ(水仙)を吹き鳴らす, which is why it made no sense.

3) Yes, it is spoken by a girl. In answer to Mike Cash's question, some of the characters, like Professor Dumbledore, speak in elaborate or old-fashioned language, while others, such as Hagrid, speak in a rough dialect. However, this character, Hermione, although she is a bit swotty, usually talks in fairly normal language, as far as I can tell. You may get a distorted view of the extent of old-fashioned or unusual language from my posts because it tends to be the unusual language that I don't understand and hence ask about.

4) This is in narrative not dialogue. So, the author's purpose in adding the furigana is to give the text a more formal tone, yes?

Yes, that's right.