What happens if I rename a theme or a plugin?

I want to hide my theme and plugins from these websites:

http://www.wpthemedetector.com/
http://whatwpthemeisthat.com/

In order to do that I thought of renaming the theme (from style sheet) and folder.

1. Will this modifications affect to functioning of my site?
2. What happen to theme or plugin updates? Will I be able to update without any problem? Do I have to make those customization again after an update?

Highly appreciate any advice,
Thanks in advance!