[theme-Corporate Lite] Specific questions

Hello,

this is the first time I use word press, and I have the following questions:

How can I change the font size of the body text (and it would actually work)?
How can I remove the sharing to social media buttons on all pages?
How to add images to the Homepage Sections?
* the Homepage Sections is the part on the home page under Hello

Link to home page: https://www.financeprivate.com/financeprivate.com/

thank you in advance