For delete format in comments, I recomend
Comments Cleaner which has a wide choice of cleaning option in comment field.
"Mass Search/Replace" and "Comments Cleaner" can be executed by "Action Chains", this 3 are a powerful combo.
I would notice that I created "Mass Search/Replace" to make multiple search/replace operation with a more ergonomic and readable configuration system than "Action Chains". The implementation of "Action Chains" is good for one or two search/replace operation, but if you wanted to do more than 3-4, it quickly becomes unreadable and complicated. With only one operation, your good (for now).
And about 'resize image': You said resize the cover image? I don't think it's possible in any plugin. I recommend you ask for help in the thread
Action Chains.