Thank you for reaching out. I’d be happy to lend a hand with this!
You can change the font size by changing the Body text from Regular to Light or Extra Light. However, if that doesn’t reach your desired font size, then this is something that our Theme Support team can help you with. If your store is subscribed to a plan, then you’re eligible to use the complimentary design time included with your subscription for this customization. Our Theme Support team can also assist you with reducing the padding for your theme. While we’re not able to provide account-specific support via the Shopify Community at this time, we’d be happy to continue assisting you with a customization request through live chat, email, or callback. Please visit the Shopify Help Center and log in to your account to create a support request.
As for having the text being placed over the pictures, the Dawn theme doesn’t have this on the Image with text or Image banner sections. While other themes may have this, it’s something that our Theme Support team can help with exploring for you. Once again, I’d recommend getting in touch with our Support team and they’ll be able to create a customization request on your behalf.
I’d love to know if our Support team can assist you with these customization requests. Keep me posted!