No.
No.
Yes. You neither read what I said not what they said properly. php.net is talking about statically compiled in mysql support which is not used anymore in most linux distributions. They all use modular PHP now where the mysql module is loaded in form of a mysql.so file.
But if you want to mess up your setup, please recompile it.
Please post the output of:
locate php.ini
Also set:
extension_dir=/usr/lib/php/modules
in all php.ini files that you find in /etc and its subdirectories.