Another long one! Here we go:
I'm wondering what the different nuance is between these four constructions, all equating to "whether or not":
1. volitional + か + plain+まい + か: 買おうか買うまいか迷っているところ。 I'm still in two minds as to whether or not I'll buy it.
2. volitional + が + plain+まい + が: 買おうが買うまいが、私の知ったことじゃない。 Whether or not [you/he/she/they] buy(s) it is not my concern/ none of my business.
3. plain + か + plain neg + か: 家を買うか買わないか迷っている人に向けて... With regards to people who are looking towards whether or not to buy a house...
4. plain + のか + plain neg + のか: 買うのか買わないのかはっきりしなさい。 Be clear about whether or not you're buying it.
Regarding examples #1 and #2, I've read different things regarding ~まい: that it expresses intention; that it's mainly reserved for written language; that it's equivalent to the English "shall not" (I've never used "shall (not)" myself, though, and don't know the distinction between it and "will (not)" except that it's more formal); that the entailment is weaker than ~ません. At this present moment, I can't say I'm managing to get a grasp on it, frankly. The first example certainly doesn't show any intention (although this may be due to the translation, which might be closer to "I'm still undecided as to whether or not I intend to buy it", and of course this would sound unnecessarily wordy in English).
The use of が is glossed over (in the text I took the example from), except that it has connotations of things being implacable. Therefore, #3 could imply that, for example, the speaker is unable to change the outcome of whether or not her son decides to buy an expensive car; he's so headstrong that he does what he wants, and she's given up trying to intervene?
Regarding examples #3 and #4, I know that the construction in #3 clearly equates to "to buy or not to buy", and that the addition of の (as per example #4) turns the construction into one of "(do)ing or not (do)ing" something. The fourth example given is more forceful than the other three, however I'm unsure whether that's due to it being in effect a command, as opposed to the construction itself having more emphatic connotations.
I've read that the fourth example connotes waiting for someone else to make a decision (makes sense, given the example itself), whereas the third focuses on the decision itself.
Am I correct so far? If not, corrections are welcome.