You should be able to do it all with a single find & replace if you use regular expressions. I don't know the regular expression syntax Word uses.
There are also text editors with such functionality built in, such as
Ebook tidy.
For batch mode, I'm sure you could do bulk reg ex find and replaces in something like
Notepad++. Or you could do it with a command line search & replaceme tool such as
sed.
Don't have access to a Windows computer at the moment, or I'd give more detailed instructions. If you want instructions for linux (or, I think mac), I'd be happy to give them.
And while I could be wrong, I'd be shocked if calibre doesn't have this functionality built in, at least as something that can optionally be activated, as part of its conversion processes.