Would all directories need 755?
When running SuPHP or FCGI ......
You are actually going to want all folders set to 755 though looking for 777 might save you a few milliseconds over processing time over updating all of the folders but for that one isn't going to be much gain.
(**Sole exception to 755 is 'public_html' itself which is normally 750)
By the way, now I have a few websites that when accessed they bring up a file download option instead of the website.
What you just said tells me that your PHP is broken and is not working!
And what I mean by that is that your web server isn't parsing PHP scripts so the scripts themselves are just read as plain text download files by the web browsers that don't know what to do with them either.
A broken PHP installation like the one you just described can have many causes but the most common ones are selecting the wrong combination of options when compiling PHP given some options don't play happy with others. Another common issue is when the PHP binaries or symlinks get mixed up or places in the wrong directories. You also get it by failing to load the appropriate Apache configuration for your PHP type as well such as failing to load the correct module or forgetting to set the handler.
In any of the above cases, PHP itself will be broken and that will cause your PHP scripts to be treated as regular download files.
You can start with the following:
# /usr/local/cpanel/bin/rebuild_phpconf --current
(Shows you what your server thinks it's supposedly running now)
Note also the permissions that I gave you in the previous post are for non-DSO systems which specifically would be phpsuexec (cgi w/ suexec), suphp, or fcgi. It does NOT include dso (Apache module).