If you fit auxiliary driving lamps you should wire then so that they only illuminate when the main beam headlights are selected. You should also have a separate switch in series with the supply to the auxiliary lamps relay coil so that you can choose to operate the main beam headlights without the auxiliaries.
From the driver's viewpoint lamps are best positioned as close to eye level as possible (this is why the police hold torches in that strange way !!). They won't be as good low down
Make sure the lamps don't wobble, are aimed correctly, and check the voltage drop in the lamp supply wires when you have finished the job. A 5% reduction in voltage at the filament typically gives a 15% reduction in luminous intensity and a doubling of the lamp life !!
the wiring is exactly the same as the split charge sytem, (wiki) you just read the leisure battery as the lamps, and take the signal from the main beam not the alternator.
