Unify text across books

I want to update my Calibre settings - there is a few things I would like to achieve:

• have the same base font size across all books, identical to body font when the device ignores publisher style (if that even makes sense)
• have the same line height in body across books

I have attached my settings, some of them will probably need to go - what are your suggestions? Heuristic processing is disabled. I am not sure in particular what to put in Fonts and Styling. Also, shall I activate "Do not split on page breaks"? Not sure what the practical implication of that setting is.

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