Question: I often find myself changing text colors to the same color for five minutes at a time which is really unnecessarily mouse-intensive.

Answer: 
Here are the steps:

1. Press `Alt` + `/`
2. Type the color (eg. blue, red etc)
3. Hit `Enter`

`Alt` + `/` is like a command palette for all available commands. It's in `Help` menu.
No there is not. But you can try following topic? maybe it will be a solution for you, to override some keys on new ones.

<https://productforums.google.com/forum/?hl=en#!category-topic/docs/docs-community/lOia0JT4dX4>