I'm just going off my knowledge of when my best friend played an EDH deck around
Wort, the Raidmother.
First: The way the stack works I think you can do that. Cause when you
Twincast Reverberate you get another Copy of
Twincast until you Bolt for a billion something. I know my friend did something like this with another
fireball esque spell. Cause you get X copies of
Twincast &
Reverberate to copy Bolt for however much you need to kill everyone at the table.
Second: The way this works is your spell is on the bottom of the stack. When your friend tries to
Cancel it, you
cancel out his counter and unless he tried another
counterspell it would fizzle and your original spell would stack. It's basically a counter war and whoever plays the last
counterspell wins. This has happened a number of times in my EDH playgroup and can be a bit of a headache figuring out all the triggers.