At the end of the drag strip have a 1/2" to 1" dead zone with no braid. Then have braid as per the rest of the track. Just place a dead short across the braid in this section. This will give you max braking in the slow down zone. My guess is is you wont need more that one foot to pull the cars up.
Voltage? Thats up to you. Anything from 8 to 16V should be OK. Amps for a stock HO?? Im guessing 1amp per lane would be heaps.