I want to freeze shredded zucchini to make bread at a later date. Do I need to do anything to the zucchini before I freeze it?

If you add salt to make them drain, rinse the salt off or you might have salty zucchini. Then squeeze out the rinsing water well so that the shredded zucchini is quite dry. Portion out and wrap/store as you wish.

I freeze my shredded zucc on a cookie sheet. Spread it out. When frozen, break it up, transfer it to a ziploc bag and store in freezer

Nope, I'd just make sure it's really dry so ice crystals don't form around the little pieces. Also make sure you squeeze out as much air from the bag as possible (assuming you are freezing in a ziploc bag).