BQ501210: Different Tx tuning and minimal operational coupling coefficient

Hello All,

i am using the BQ50120EVM as Transmitter and BQ51050EVM 764 as Receiver.

1) What is the tuning method for using different Tx with the  BQ50120EVM

Currently there is a 247nF capacitor (designators C16,C11,C19) and the inductor = 10uH.

it is not fit the operational frequency of 125kHz.

so what is the exact formula for tuning?

2) how can I increase the operational distance ?

I can give each up efficiency and i can give up compliance with the Qi standard 
In other words what can be done in the EVM HW wise in order to work in larger distance (currently even 12-13 mm is not an option) even in the cost of working at 10-20% efficiency and without compliance to the Qi standard.

3) what it the minimal coupling coefficient  (k) that the system is working with.

Thanks

Igor