First off, this is your wedding, it's not your parents that are getting married. It's also your fiancé's wedding - not your parents'. If you want to be sneaky about the toast thing, let everyone toast as normal and when your mom brings it up, just shrug and say it was unexpected and would have been disrespectful not to acknowledge them - this is a special occasion you likely wont ever be experiencing again with your fiancé, so make it count & make it fun.

Your mom doesn't sound like a bad person, just extremely misguided and manipulated by the JWs. If she's already being pushy about toasting and giving you marriage literature, you better gear up and expect her to try and take her grandchild to meetings at every chance she gets, behind your back or otherwise.

Instead of the normal "Oh how cute, this grandchild of mine is an amazing miracle and a wonderful legacy for our families", she's been taught weekly to feel "this child could die tomorrow if it's not taught of God, and it won't learn about him from it's parents".

Your dad sounds fairly chill about everything. Maybe talk your concerns over with him and he might be able to reel your mom in while the kid is around. I'd also be a tad more selective about the Bible Stories thing.....when my sister was younger, she'd run around telling other kids she knew that they were going to die in a fiery apocalypse and it would disturb them enough to send them running away crying to their parents in fear. Reading a Disney book about Hercules to read to your kid is done with the intent to entertain them, reading a Bible Stories book is intended to indoctrinate & instill fear of death in them.