How do I tackle phone-microcontroller BlueTooth communication?
Normally, Bluetooth modules have a so-called "AT" interface, meaning you can send commands to them and results back using AT commands modeled after the old Hayes modems of decades ago.  But I was unable to find any such interface for this module.

As far as I can tell, the RFM70 module is not Bluetooth -- it operates in the 2400-2483.5 MHz ISM (Industrial Scientific Medical) band, which is the same frequency band used by Bluetooth but using different protocols.  People are using the RFM70 to "talk" from one microcontroller to another (for example, remote control of a device), but not to communicate to and from Bluetooth devices.

I see where RS Online was claiming it is Bluetooth, but its not.

There are many libraries out there to help to interface to a RFM70, but most seem to be for the Arduino.  However I was able to find one, while not targeting the STM32 directly, seems to have been ported to several different micros so perhaps you can modify it for your use.