LT1711 maximum supply voltage and maximum input voltage
Can I power it from 12V and GND?


The supply voltage from \$ V^+  \$ to \$ V^-\$ is 12.6V, so yes. This is found in the absolute maximum ratings section. If you violate the conditions in the absolute maximum ratings, you will have loss of functionality or destroy the part. This is the first thing you should read when looking at integrating a part into a design. Staying withing the absolute maximum ratings does not mean the part will function the way you want it to.


  Can I put a signal with 8V amplitude into one of its inputs?


Yes as long as you don't exceed ±12.6 between pins and don't exceed the current.


  Differential Input Voltage ................................... ±12.6V
  Input and Latch Current ..................................... ±10mA


You also have a common mode range to worry about.