Php 5.6.5 won't work very well
Solution 1:
You have php, but not the apache module for php
apt-get install libapache2-mod-php5
You may need to enable the module...
a2enmod php5
Restart apache and you should be good to go.
Without this module, apache doesn't do anything special with PHP, and just passes it through as text. You saw a blank page for <?php phpinfo() ?> as that looks like an empty XML document (view source will reveal all)