You can change the theme and copy of the embeddable UI in the Editor section of your campaign on Gather.

You can choose whether to include a header image as part of the embeddable UI or not. Here we added an image to the embeddable UI for demonstration purposes.

Yes. There are two types of embeddable html tags you can add to the page. One gives the UI its own independent scroll and the other uses the same scroll page. Testing the page on mobile as well as desktop will give you a good idea as to which option to choose.

The referral dashboard can be launched from any page on the site, in an overlay sidebar. It is also worth considering adding a landing page that is specific to referred friends. This is where you can communicate your brand to them, and why they have been referred. Having a landing page specific to friends means your customers will be sharing a link to that page. When a customer shares their link on social media sites like Facebook, a page image can shown as part of a post. This means that invited friends would view a relevant invitation post image on their Facebook feed (e.g. an image with the sentence: "Your friend has sent you a gift!", which would help increase click-throughs.

If you can create a page that is behind a log-in and embed code in it, you should be able to restrict the referral dashboard to logged in customers.