Sensors works when you apply brakes for front sides and when shift to reverse for rear side then front side automatically off when apply brakes in reverse, otherwise all time they remain off all time.
No too much alteration needed only drilling holes in bumpers for sensors is major task then set loop of wires in rear wheel well & connect one wire to brake bulb wires & second to reverse connection, you need to carefully remove right side rear plastic cover where jack & tools placed.
There's 2 types of sensors available in market one is for both front+rear 2nd for reverse only, i bought from plaza khi, in lahore mughal auto montgamry road you can find.
Leds for low beam H11 is safe won't problem to others, feels like genuine bright light like in Audi or Merc, no challan at all, cost you depend on quality, good quality is about Rs.3000 try to get w/o fan for no noise its used large heat sink w/o cooling fan.