yes , and it is regarding Canon sensor layout and read out, more Mp means also higher dynamic range due lower read out noise from the individual pixel, more Mp is a easy way to increase Canons dynamic range, but the analog signal path way can never be as short as, for example in the Exmor and it depends on the early AD conversion in Sony lay out
In other words, no. There are many other factors you mention above. Just increasing sensor resolution alone isn't going to absolutely increase DR.
Taking current type Canon tech going to more MP tends to very, very slowly lower SNR and very, very slowly increase DR. The gains in DR going from 23MP to 50MP won't be a whole lot and SNR loss won't be a whole lot. In more extremes like 8MP vs 250MP it can matter more.