Proper directory permisions for module installation?
The module directory has contested ownership. In your case, using the FTP set up from the browser, the modules directory (and subdirectories and files) need to be owned by the FTP user you are logging in with.

For example: if you are ftp-ing in with myusername then the ownership on the directories and files are most likely be myusername. That is the default configuration for most FTP servers (ProFTPd for example).

$ chown -R [myusername] [pathtomodules]


If you are updating Features (or configuration in Drupal 8) from the Drupal backend you'll want the modules directory owned by the same user as your web service runs as. Then you can have your permissions set to something more reasonable.
If you grep ps for Apache, nginx or httpd you should discover the user that's running the process. 

$ ps aux | grep -i 'www\|apache\|nginx'
$ chown -R [username] [pathtomodules]


And finally if you are using drush dl you'll need the owner to be your SSH user.

In all cases you can set the strongest permissions with the following. Remember the webserver needs read on all files and execute on all directories. This command will give you 755 on directories and 644 on files.

$ chmod -R u+rwX,go+rX,go-w [pathtomodules]

The first two numbers in your ls command are user and group. That may be a numeric match for your web service user above. The third column is size.