Learning the ropes - modifying in-theme, or pieces of themes?

Let me start by saying that I'm new to the building side of web dev, and a designer/strategist by trade. But I want to be able to launch a basic website quickly and easily on my own for super small clients where the profit margin is slim.

We loaded GP Premium, Elementor Pro, chose the Artisan theme, started a child theme, and began customization.

Where I'm stuck now is a couple of newbie issues -

1 - I love the theme footer in the Artisan theme, but I seem to have wrecked it in working on customization. Can I re-load the theme footer somehow?

2 - Can you 'mix' theme elements? Example, Can I pull in theme code from another theme, like the Target theme?

3 - I can't figure out how to adjust the master color palette (if that makes sense!) There's many color options in customizing the theme - is there a 'master' color set that will show in each of the areas, Body, Header, etc?

Thank you a million for the guidance!!