If the new dynamo has a different size, the location may be a bit off when using the dynamo update tool. In that case you still need to check every display separately if everything is lined up right. Update tool works great anyway.
On the second question. Bulkedit can't add, remove or rename parameters from modules, only change values of existing parameters. It also can't delete modules from the database.
If the modules are class-based, it's of course simple to modify the class and then change the values with a bulkedit in all the instances.
If the modules are template-based, I think the only way is to replace the modules. Basically delete the old ones and bulk-edit new ones. Tip: work with class-based whenever possible.