Hello lestanin-android,
Thank you for the queries.
1. You need to edit the css codes, font-size on style.css file and change the size as your required size. Please try by changing the font size number.
2. If you are using the latest version, you will not get the theme with child parent page because we move it. Users became confused so we change the concept. Check this link to make one page site.
Hope, this will help you.
Regards