I don't know how many times I have wanted to remove that hulking pagefile.sys file, but that's not my point.
Since there are newbies here, I think it would be best to treat them with some respect and inform rather than mock.
Apple does in fact provide an application that exposed /usr, /etc and all the other unix directories -- Terminal.
Filenames beginning with "." are not hidden. They are not listed by default by the program ls. 'ls -a' will list these files along with the others.
There are critical files that are not hidden. It may seem obvious, but you should not go about deleting, editing, renaming, etc. files in your System, Library, and even Applications unless you know what you are doing. If you know what you are doing, you are probably not changing any of these files by hand with the exception of application you installed.
Don't listen to anyone who says just 'rm -rf *'. They are not your friend. And if you think you know what you are doing never 'rm -rf some_prefix*' If you get into that practice, you will one day add a space and delete everything. If you don't understand that, never use rm and always delete files using the Finder.
I am not familiar with NO-IP or the Fusion, but I think the need for dynamic DNS is *optional*. It is required if you want to make your NAS visible to the world. Is that what you really want? Dynamic DNS should not require any app being installed on your computer -- register your name with your provider, NO-IP here, and setup port forwarding on your router to make any devices on your home network visible to the world. All of this is managed through your web browser.
You did not say how you deleted /usr. I am suprised the Finder allowed you drag it to the Trash. I guess MacOS X is too /usr-friendly. (Sorry, pipj missed the chance for that groaner)
The mac is intuitive, but all intuition is learned.
And They Said the Mac Was Intuitive