Depends on how it's built, show an example.
yes Depends on how it's built
I am just going to say no, no it is not. Look how commonly used they are I mean this website that is the home of thousands and thousands of SEO services uses drop down menus as seen above.
Tiny things like that are not something to worry about when it comes to SEO because if you do you'll just slow yourself down,
I don't think they are but it really depends on how it is built. But they could have some negative impacts.
As far as I know, they are not.
I am not entirely sure but I think that if the URLs linked to by the drop down items are visible in the code then Google will follow them so it should not be a problem.
It depends some times...