salaam brother Dawood,
1) You said, quote: “If we assume that “new change” is some way related to guiding to a straight path, then we must conclude that prior to this change, they (Muslims, including the prophet) were not guided to the straight path or were not a balanced community?”
Every successive revelation of Quran ayat over time is simply a continuation of the same goal of guiding etc, even if a future ayat reveals something not discussed in prior ayat, it doesn’t mean since they were not aware of it before they were not guided, the new ayat are simply building upon what came before. In these verses, 2:142-150, it is discussing a change of qiblah/focus (a change in strategy if you will) but this does not necessarily mean a change in the end goal.
2) You said, quote: “the concept of many qiblahs is wrong”
Quran 2:145 says, quote: “they would not follow thy qiblah, and nor will thou be a follower of their qiblah, and nor some of them are followers of each others qiblah...”.
Thus, Quran unequivocally discusses a minimum of 3 qiblah, and the wording obviously implies more but a minimum of 3 we can say for certain.
3) You said, quote: “Please note, the phrase “wamin ḥaythu kharajta” is a clear and unambiguous reference to going out for prayers” and “ It is therefore abundantly clear that Muslims are directed to face toward the masjid Alharam when praying or doing salat.”
Brother, the word "salat" is not mentioned in these verses. Granted, that is a common interpretation but that does not change the fact the word is not used in these verses.
(ps - that extract I originally quoted was taken from here: www.mypercept.co.uk/articles/meaning-masjid-al-haram-Quran.html if you wanted to check it further)