But please guide me how this is done (is it done in the G-code generated where the g-code would be generated in a way that it is offset already or is it done in LinuxCNC itself after the g-code is already generated but does not have the tool offset built in)?
Take a look at G41 G42
linuxcnc.org/docs/html/gcode/gcode.html#sec:G41-G42
Often it is taken care of when the g code is generated, but if you are starting with a cad program and you know the size tool you will use you can apply your offsets there.
There may be gains in speed or torque when selecting parallel or series connections but you may also want to factor in the available power supply's voltage and amps to get the best combination.
But you may be getting a little off topic and want to post your questions as new posts in their categories to get the best possible results.
Rick G