Opera, Chrome, Firefox, IE, and Safari are the big ones. You'll need multiple versions of FF and IE. Or, if you are lazy, you could get http://browsershots.org/ to do all the work for you.
"public_html" is the folder you need, not "public_htm". Also, the index file has to be named something recognizable, like "index.html", "index.htm", or "index.php".
Why not get a FTP client?
You can build a website via your browser.
There are tutorials in Cpanel.
Helions were a form of currency that are no longer used.
I am installing phpBB 3.04 via Fantastico to confirm. If this works, I will try to update from this to 3.05.
UPDATE 1: 3.04 via Fantastico worked without any issues.
On another note, why is phpBB 50mb via Fantastico and maybe only half that through manual install? o_O Or maybe I'm missing something...
Update 2: http://nephelokokkygia.co.cc/forum/
*Woosh*
I successfully installed phpBB 3.05 through first installing 3.04 via Fantastico and then updating with the automatic update package found here.