Powering the Maestro from your RC receiver by bridging the VCC and VRC pads on RC switch #1 should work. However, you should also connect the VCC and VRC pads on your second RC switch, since VCC needs to be supplied with power for the board to work. If you connect things the way your image002 schematic shows, bridging VCC and VRC on the second RC switch will power the switch from your RC receiver.
In general, all electronics in a system should share a common ground. So, because your switches and Maestro are being powered by your RC receiver (i.e. the ground node on the receiver is shared between all those devices), you can get away with only connecting the OUT pin to the Maestro in order to read it. However, adding the GND connection between the second RC switch and your Maestro will not damage anything.
Also, I suspect you understand this, but just in case it was not clear: you will need a separate input channel on the Maestro to read each digital output from the RC switches (i.e. you would need a total of two channels like your schematic shows).