LU
(In the order that you intended)
“It is kefira to think that Hashem is not All-Powerful.”
firstly I agree though
a. That isnt what you said, you said “and He is the ONLY One who makes things happen” that is not the opposite of him being “All-Powerful” it isnt kefira to maintain Hashem allows hishtadlus to have an affect whether it violates Halacha or not.
b. As mentioned even if the the Ramabm says what yo uclaim, as mentioned, not all agree
2.
” provide sources explaining what the other views are and who has them ”
ITs much too long a discussion. For a starting point read through variosu Rishonim on “Veechazak es Leiv PAroh, while the notion of bechira is not the direct subject at hand, it is related since a simple reading of your narrow definition of hishtadlus doesnt allow for bechira. Yes there are those who answer R’ Dessler in particular was a strong proponent of your position.
Besides I dont have to provide sources IF Hashem wants you to know them you will know them whether I provide them or not.
3. ” I was referring to LC’s post”
Not sure how yo ureached that “if only i could believe that evils would be dealt with by gedolim and responsible lay leaders without airing them in public” in any way disputes “Belief in Hashem means believing that He is all Powerful and that He is the ONLY One in control, and He is the ONLY One who makes things happen.”