Each D.I. Output carries the signal of their respective channel. By default, the signal sent to the DI is post EQ and without the effects. It is possible to have a technician change the internal jumper so the DI are taken after the gain but before the EQ and without effects.
The footswitch port expects a latching two button footswitch. Unlatched / momentary footswitches will not work.
On the amp side, you would use a mono 1/4" Jack into the Line 2 output. On the mixing console side the same can be used as the signal is mono. However it is always a question what the aim is, using the console. To note, Line out 2 is the signal addressing the power amp, which will be around or above +4dBU. While Line out 1 is the same signal reduced to be in the range of -10dBV.