What is a proper way to send information from an HC-05 (Bluetooth module) to a phone?
The usual way of doing this is to use a microcontroller to interpret the inputs and then send your information to the HC-05 module via UART. You need to make the communication protocol yourself, which is probably a good thing. Since you want 12 analog inputs you might be facing some difficulty finding a small microcontroller with that amount. 

My suggestion for this task would be to use an analog to digital converter chip (ADC) for the inputs and send this to the microcontroller, which interprets the information and codes it according to your communication protocol and then sends it to the HC-05. An 8-channel ADC can be seen below. Such an ADC connected to the ATtiny85 communicates with SPI or I2C, which are bus protocols needing few wires.
  

Alternatively, you can use something like a Teensy 3.6 as it already has enough analog inputs. Of course it's bigger and way more powerful than what you need for your purpose. This will be up to you and how much convenience you want in your project. Teensy 3.6 pictured below:



If you want real good convenience Adafruit designs a series called Feathers. These are Arduino compatible microcontrollers with built in Bluetooth functionality that are easy to use. The Feather M0 features 10 ADC channels, which is almost what you want. By searching their range of products, you might be lucky to find a 12-channel one or you could simply use the Feather M0 and a small 2-channel ADC so you have 12 channels.



https://www.adafruit.com/product/2995