Your fine to leave it in d with your footbrake on at the lights, its the 21st century these days so the car knows your stopped with the brakes on and releases the clutch or does some magic in there, when you let go of the brake you will feel about half a second pause then the clutches will kick in and it will start to edge you forward. If by any reason you want to stop and put the handbrake on you will have to put it in neurtal orelse it will try and move forward. Your brake pads wont wear out sat still at the lights
Say your at the lights in neutral with your handbrake on the procedure is press the footbrake put it in d, release the handbrake and lift your foot off the footbrake unless your doing a hill start then put it into d let go of the brake then release handbrake about half a second later.
You will get used to it soon but it took me about a month to get fully used to it and i like it more and more all the time, 98% of the time im in manual using the paddles. Ive drove a ferrari 360, aston martin, audi r8 and lamborghini gallardo and none of them systems where as nice as dsg