I have never had a problem with my baby rats dying but make sure to not wean them early (maybe try giving them an extra week) and make sure food and water is accessible to the babies.

I would recommend culling rats with tumor. I would not recommend feeding them to your snake.

Rats will usually only eat their babies over stress or lack of protein. Older rats may not be able to take care of a bunch of babies so she may have to eat some or all.

Hope this helped