Webfont not rendering in child theme

Hello,
First of all, thank you for this extremely productive theme.
I’m discovering the theme at the moment and meet some problems.

First: In my child theme the webfont for the site title, page header and post title are displayed in serif unless I defined Roboto Slab.
In the page source I see Roboto Slab defined in the inline CSS.
What did I, resp. what goes wrong?

Second: At the end of a message content I see: Written by “[author name]”, how to get rid of that?

Cheers,
John