Hello,

yes it is possible, to make master slave mode.
Slave-slave communication requires a PROFIBUS-DP master, which supports this
data exchange function; for instance, these are all of the SIMATIC S7-CPUs with
the property "Equidistance" (isochronous) in the catalog.

there is an example in the internet: http://support.automation.siemens.com/WW/view/en/60602336
It is for the G120D, but in general it can be used fot the G120 modular (CU240x-2DP with the PM240) also.
At sensorless operation instead of torque control it is recommended to operate the slave as a slave drive with overdriven speed control.
(Please find also a briefely description in the example).
The master can be driven in sensorles speed control.

Hello,

there are many possibillities, one will be via the rfg of the master:
r1438, speed setpoint from the master via slave to slave communication (e.g. r2050.x) to the slave, scale it with a free function block e.g. to 105% and connect it to p1160 speed setpoint 2.
r0079, limited torque setpoint from the master via slave to slave communication (e.g. r2050.x) to the slave p1522, torque upper limit, and p1523, torque lower limit. Ensure, that p1525 is on -100%, if p1523 is a positive value.

Please find the function diagrams -6040-, -6060-, -6630- in the list manual.