Hi,
HikaShop 1.6 was not PHP 5.4 compliant so it will display warning notices.
You can update HikaShop yes. You can also deactivate the PHP notices which should be disable in production mode (much better).
It is not real errors, just warning notices ; it does not generate any kind of problem instead of display something in your page.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.