There is no option to change the dropdown icon. To change that, we have to modify theme code again.
Which dropdown icon do you like?
And for the menu hover color:
The default hover menu color is site primary color.
So if you want to change the hover menu color, please change the site primary color.
Also you can change the menu hover style on theme option panel->header->menu like screenshot.
If you have any other problem, please contact us again.
Best Regards, C-Themes