cmd + L will select the entire url, then you can use cmd+C and cmd+V for copy and paste.
You can also click on the favicon on the left of the url to select all the web address.
Finally, if you want to share a link via mail shift+cmd+I will open a new mail with the link pasted in the body and the title of the webpage in the subject. cmd+I will open a new mail window with all the content of the webpage in the body.