The Paramix circuit uses unbalanced inputs. If you have balanced XLR signals coming from the amp DI and the mic, you would only use the non-inverted signal from pin 2 and the ground at pin 1 to send to the Paramix. SInce you are only sending these signals a short distance from the amp and mic to the enclosure, balanced XLR is typically not needed.
The Paramix has a separate level pot for each signal. This permits mixing the two signals in the ratio you desire.
The output of the Paramix is an unbalanced non-inverted signal. You would need to add a separate DI circuit (box) to change to a balanced signal with a XLR connection. If the distance to the band mixing board is not excessive, you probably don’t need to use balanced XLR for that line. Unbalanced 1/4″ plugs/jacks would suffice. I suggest you try using unbalanced first before buying an additional DI to create balanced XLR. Be careful to turn phantom power OFF at the mixers!
A ground lift switch is useful when running signals to a back of house board that has a separate mains supply. Sometimes this creates ground loops and hum. For an on-stage system, I doubt you would need it.
A phase switch simply reverses pins 2 and 3 in a XLR connection. Sometimes it is useful to help control feedback or to provide stereo imaging.
If you wish to build your own DI with balanced output, I can provide a schematic. I hope this helps.