I kind of simplified it a bit …
Occam's razor stipulates that when two presented ideas compete for the same effective conclusion, the one which relies upon the fewest unsupported assumptions is most probably the correct one
It doesn't really apply to things which can be proven through investigation or experimentation. Many try to use Occam's razor in lieu of experiment/investigation… But even so, erroneously assume that it means "the simplest" when it's less to do with simplicity and more to do with how many assumptions are made.
What is often not understood is that occam's razor doesn't end at the initial statement, but extends to every evidenced challenge to it. The more assumptions required, in face of the evidence conflicting with the first assumption, the weaker the theory becomes. The more internally consistent theory, therefor, is more likely to be true than one which must bring in new assumptions to explain the conflicts of evidence.
See above.