Thanks for the thought!

All the shortcuts can be changed, just follow the steps in https://support.mozilla.org/en-US/kb/manage-extension-shortcuts-firefox, then click on the shortcut for 'Find in current tab' and type a new one.

To change the colours:
Open the popup with the Mark My Search icon (in the toolbar or in the extensions list)
Click 'Open options'
Find the comma-separated numbers list. These are the hue values for colours. For example, 300 is purple and 360 or 0 is red. Edit these however you like.
Press Enter (or the Save button) to save you changes

I'm sorry it's complicated at the moment. The next version will make it easier :)