(a) It seems to me that the order of the questions, according to the Pesukim is very Meduyak, based on the sequence of the answers (not the questions).

1. Firstly, we cite the Pasuk "ha'Boker Or ... ", where the answer is from the words themselves 'Mi Kesiv ha'Or Boker ... '?

2. Then, we cite the Pasuk "u'che'Or Boker Yizrach ha'Shemesh", as if to say, 'But didn't we just say that, had the Pasuk said "Or Boker", we would have had a proof that 'Or' means day? So what will we answer now'? And we answer exegetically, according to the context.

3. Now, we do what you advocated, and ask from Bereishis, where 'Or' seems intrinsically to mean day; and we answer that "la'Or ... " is a verb ('le'Me'ir u'Ba') and not a noun.

4. But, we probe further, what will we do with the Pasuk in Tehilim (which is connected with Bereishis [i.e. the Creation]) "Ha'leluhu Kol Chochvei Or", where it cannot be a verb. And we answer initially, that it is nevertheless a descriptive verb ('stars that shine'), and finally, that it means 'light' (and not 'day').

5. Now we ask from the Pasuk "le'Or Yakum ... ", which seems clearly to mean 'day' (the opposite of 'night', which the Seifa of the Pasuk mentions); but this time, we answer that "Laylah" and "Or" are not meant literally, but are a Mashal; the former means 'doubt', and the latter 'certainty'.

6. The last two Pesukim in this Sugya do not seem to teach us anything new. It would seem that the Sugya cites first the Pasuk from Iyov ("Yachshechu Kochvei Nishpo ... "), since the previous Pasuk was from Iyov too. It ends with the Pasuk in Tehilim "va'Omar, Ach Choshech, ve'Laylah Or Ba'adeini", as that is the only remaining Pasuk from which it is possible to ask on Rav Huna.

(b) I saw a number of answers to your second question in the commentaries.

1. MAHARAM CHALAVAH answers in the name of the RASHA that the extra proofs are 'Yagdil Torah ve'Ya'adir'. In other words, the Gemara brings another proof from another Mishnah or Beraisa even though it has nothing to add to the previous proof in order to broaden the Torah and to make it more glorious.

2. MAHARAM CHALAVAH adds a second answer from the RASHBA, that the various questions were asked and answered in different Batei Midrash, and they were all collated later and inserted in the Sugya.

3. RABEINU DAVID answers that the Gemara initially sets out to prove that 'Or' means night (like R. Yehudah) and not day (like R. Huna). This, however, does not provide a clear-cut proof against Rav Huna. The fact that the Tana calls night 'Or' in one place, does not mean that it cannot also mean day somewhere else.

4. With regard to the first proof from the Beraisa of 'Bodkin 'Or l'Arba'ah-Asar', perhaps we can argue that even if Rebbi Yehudah calls night 'Or', it does not mean that the Rabbanan do.

That is why the Gemara brings proofs from many Beraisos that 'Or' always means night. The last straw is from the Beraisa of 'Leil Arba'ah-Asar Bodkin', which is the exact paraphrase of our Mishnah and which disproves Rav Huna entirely (if he interprets 'Or' as day, like we thought until now).

b'Virchas Kol Tuv,

Eliezer Chrysler