Some questions about EPUB to PDF conversion

Hello.

Recently I have been trying to convert some EPUBs to PDFs using calibre through the command line and have some questions.

Is there a way to set a base font but have it be overwritten if the EPUB has other base fonts set? I'm using --embed-font-family and it works like how I want with EPUBs which don't have any style or embed fonts but I'd like it to ignore that option if it finds styles with set fonts. The manual says it might get ignored but that doesn't seem to be the case. It does ignore it for some of the text, like if there's italics it'll use its embed font instead of the one I set, and the one I set shows italics fine in other documents without embed fonts. Without that option (--embed-font-family) all the embed fonts get rendered fine.

I'm also currently facing an issue where some images get split (they bleed into the next page). When using the UI conversion this doesn't happen. I tried using both (UI and command line) without any additional options and (I think) with the default settings on the UI and it generated different results.
Any idea what might be causing this?

And is there any options for handling images at all? Like making images ignore the set margins.

Thanks.