they went blind because of what the dwemer forced the falmer to eat
This is incorrect, you can't pass on acquired characteristics, it must be that the snow elves with bad/no eyesight survived and the ones with good eyesight didn't, over time they evolved to be blind.
Just eating something that makes you blind doesn't alter your genes, the ones with bad eyesight survived and passed on their genetic material. But then again, this isn't earth, who knows.
but i wonder, if the past and present falmer were to breed, how would that turn out? like partially blind maybe slightly more civil but still always pissed off race of mer?
Well it's unlikely they could produce fertile offspring, or even produce offspring at all. Over the thousands of years that the falmer evolved, to much variation has occurred for them to be classed as the same species.
The Snow Elves are the Falmer
The falmer = snow elves isn't correct, the falmer have evolved from the snow elves over thousands of years.
At some point some sort of selection pressure was forced on the snow elves, the ones with bad/no eyesight survived and the ones with good eyesight didn't, thus the falmer speciated from the snow elves (given that falmer are a different species, which is a logical assumption).