Questions about homepage

Hello, 1/ I'd like to display some text on my homepage, above the articles from the blog. So I created a page called "Home" with the text. I also created a blank page called "Blog". In the theme customization menu, in the home page settings, I set the home page to be a static page with "Home" as homepage and "Blog" as articles page. My problem is that the articles do not appear on the homepage. Where did I go wrong ? 2/ I'd like to change the width and the height set in header image. How do I do this, and will the size of the image be changed in all devices as well ? Thanks for your answers.