I would suggest you to go for Application Associate Certificate as Technical Certificate is for those who will install HANA, design system architecture and implement it while
Application Certificate is basically for those who will be develeoping models and other stuff in HANA Studio
PHP works very well with HANA and you can check this link for you
http://scn.sap.com/community/developer-center/hana/blog/2013/01/21/php-rocks-on-sap-hana-too
Knowledge of Java is needed only when you use HANA XS otherwise knowledge of SQL and SQL Script is more than enough