Well we can install it for you but there would be a fee involved to do it if it still requires command line access.
Yep, PHP4 is the default version. PHP5 needs to be enabled in your .httaccess file.
I can show you the link in the forums but I think its best you use the "search" option and simply search for PHP5 there are only a few topics in here regarding PHP5 and one of them is how to enable it on your site.
If you cannot find it let me know.