Order of sentence's parts in building sad-mooded rhetorical question

Question

太陽を最後に我々は見たのはいつだ?

literally: The Sun last time we saw-state when are?
meaning: When did we last time saw the Sun, f**k!?

context: it is a sad rhetorical question about bad rainy weather.
It is not a question like: give me precise hour and minutes when we saw the Sun last time.
This is a sad statement, that weather is bad and cold is annoying and everybody is depressed, and it was raining for so long, that we all even forgot when the last time it was a sunny day (means good weather).

My questions are:

1) As far as [we] here is not about particular group, where everybody knows everybody, it is about population of a city or even region. Does it mean that [wareware] is more appropriate, than [watashi-tachi]?

2) I'm a noob and still do not have feeling in what order of words it is better to please Japanese ear.
So, question: is the order of parts in this sentence ok from Japanese point of native hearing or it sounds pretty weired? If so, what order of parts is preferable for building such a rhetorical question with sadness mood?

3) Imagine if this question is not sad and not rhetorical, but positive and precise with meaning like: tell me exactly when we were seeing the Sun the last time.
Rhetorical question means, that noone expects the answer.
Hearing rhetorical question people just say: yeah, the weather is shit.
But active positive question does build expectation of precise answer like: I think that last time I saw the Sun at 13 o'clock.
So, do I have to change something in this sentence or it is just a matter of intonation?

4) Is making noun from verb 見る => 見たの (past tense + no) and by this turning into [da]/[des] sentence, is this trick weired for Japanese ear? Is this trick too much? Is this trick too literal or too bookish? Maybe native speaker would just use past tense without [no]-ing verb to noun? Or maybe turning verb to noun IS the true Japanese way of saying things like that?

5) Is 最後に [sai-go] last time ok for this case or maybe it sounds unnatural for Japanese ear? If so, what adverb would native Japanese would use in case like this?

6) Is using を in 太陽を is just my European way of thinking and in building the true Japanese style, I should [wa]-ing the Sun like [太陽は...]?

太陽は最後に我々は見たのはいつだ?

If this is more preferable for Japanese style way of saying, isn't it too much [wa] for one sentence? In that case it will be 3 [wa]!!
Does it mean, that to avoid 3 [wa] I should [ga]-ing something?
Maybe [wareware-ga]?
Or 3 [wa] for one sentence is fine?

7) I saw many examples and most of them start with [wa].
Does it mean, that it is unnatural for Japanese to start with [wo]-ed word?
If I use [wo] for the Sun, does it mean that I must put it after all [wa]-ed words in the sentence?

8) I saw many examples and I noticed, that many authors use comma for the first word and they even omit [wa]!!

For example

雨の日、よく ...

literally: Rainy day. Often I read books and watch tv.
meaning: On a rainy day I often read books and watch tv.
meaning+: When it is a rainy day, then I often read books ...

When I first saw it, I thought: if comma ok, why do they omit [wa] or [ni]?

Why do they not using like

雨の日に、よく ... (European style) On a rainy day I often ...
雨の日には、よく ... (European + Asian style) On a rainy day, well... I often ...
雨の日は、よく ... (Asian style) Rainy day. [pause] I often ...

So, my question is what about comma?
Does comma so powerful in Japanese language, that it can kill even particles and work as super universal particle?
If comma is so super powerful is it allowed to use particles before comma?
Are my [雨の日に、] and [雨の日には、] and [雨の日は、] legal forms?
Or comma means no particles, and only [雨の日、] is legal?

And therefore if I want to use comma for my initial example, what option should I prefer from this list?

太陽を、...
太陽をは、...
太陽は、...
太陽、...

To my feeling of role of Japanese comma I feel, that the last [太陽、...] is more Japanese way, isn't it?

Answer 1

太陽を最後に我々は見たのはいつだ?

First of all, this sentence is incorrect. の is a formal noun and 見た modifies の as a relative clause (this construction is also known as a cleft sentence). You basically cannot use は inside a relative clause. The correct sentence is:

太陽を最後に我々が見たのはいつだ?
When did we see the sun last time?

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1. Does it mean that [wareware] is more appropriate, than [watashi-tachi]?

Whichever works fine, but 我々 sounds stiffer and 私たち sounds politer.

2. what order of parts is preferable for building such a rhetorical question with sadness mood?

You can construct a rhetorical question in the same way you construct an ordinary question.

3. do I have to change something in this sentence or it is just a matter of intonation?

It's a matter of context and intonation.

4. Is making noun from verb 見る => 見たの (past tense + no) and by this turning into [da]/[des] sentence, is this trick weired for Japanese ear? Is this trick too much?

No, の as a nominalizer is not a "trick", and even a three-year-old kid can use it. Learn about a cleft sentence, too.

5. Is 最後に [sai-go] last time ok for this case

Yes.

6. Is using を in 太陽を is just my European way of thinking and in building the true Japanese style, I should [wa]-ing the Sun like [太陽は...]?

Basically, you cannot have more than one topic in a sentence. You already have は after の, which means the topic of this sentence is a noun clause, 太陽を最後に我々が見たの ("our seeing the sun last time"). The corresponding comment is いつだ.

It's possible to make only 太陽 the topic, but you have to drastically change the format of the sentence: 太陽は最後にいつ見たのだろう?

7. I saw many examples and most of them start with [wa]. Does it mean, that it is unnatural for Japanese to start with [wo]-ed word?

No. Although relatively less common, you can safely start a sentence with a word marked with を.

8. many authors use comma for the first word and they even omit [wa]!!

It's hard to explain what is going on if you cut out a sentence like that. Note that 雨の日 can work like an adverb, just like 昨日 and 明日. Even in English, you can start a sentence with "Last year, ..." or "Today, ..." with a comma but without any preposition. In general, the role of a Japanese comma is not as important as an English comma.