First, yes, TextEdit can do this for you. First, make sure that you are using Plain Text format (Format->Make Plain Text). Then go ahead and save the file and close out of it.
Next, in the Finder, do a Get Info on your file. Expand the Name & Extension field and delete out the ".txt" bit of your file name.
Note -- naming a file with a "." as the first character is sort of uncool with the Finder. You can do it, but your file will be invisible -- you'll have to go into the Terminal to deal with it. If you save it with a "." as the first character, you won't be able to do the Get Info bit. So, save it without the "." and then upload it and change the name to include the "." when it's on the server, after you've uploaded it.
TextEdit aside, if you don't want to deal with a command-line text editor, download
TextWrangler and when you install it make sure to install the command line tools, just for added features. At least in my quick test, TextWrangler does not add an extension by default. It even has "Save to FTP Server" options. After you save it to your site, in TextWrangler's FTP window just choose Get Info and set the permissions however you want. (Plus, the ability to invoke it from the command line on any file is nice, particularly for really long config files like Apache's.)
Otherwise, yeah, get familiar with some command line editor and a few commands. Setting permission on the command line would be like this:
<code>chmod 644 name
of_yourfile</code>