In the second half of "The Magic Bag", Felix refers to Professor by name, even though he hadn't introduced himself to Felix. So how would be know his name? Simple—he's already met him before.
Master Cylinder's wheezy old man voice may be unimpressive compared to other cartoon villains, but considering his original body was blown up in a lab accident, it makes sense that he'd have some kind of vocal impairment from his injuries and cyborg body, ala General Grevious and his constant breathing problems.
It seems odd that Poindexter was able to exploit the Magic Bag of Tricks in "Martin the Martian Meets Felix the Cat" considering how the bag always refuses to serve Professor when he steals it, but it makes sense when you think about it—the Magic Bag is sentient. It's not that Professor technically couldn't use it, it's just that the bag knows he's a bad guy and won't let him use it. Poindexter can be a brat, but he's ultimately good at heart, so the bag has no problems letting him use it.
