INA317: Gain setting of instrumentation amp

Hello Expert,

I have questions regarding gain setting of INA317.
Would you answer following questions?

1. Is there any recommended way of changing Rg?
   1. We think use digipot or switching register array by some switch. Is there any concern regarding this method? 
2. Could I change Rg when the case of input signal is still remained and power is supplied to INA317?
3. Is there any instrumentation device which can change gain digitally? For example, using I2C or SPI, using selecting pin status as binary, etc...

I'm looking forward to hearing back from you.


Best regards,
Kazuki Kuramochi