I am starting an N-scale DCC layout. Some old HO scale stuff came into my hands. Will a RailPower 1370 Powerpack be of any use to me for my DCC layout? Additional question - thoughts on Atlas code 65 vs code 55 vs code 80? Kato Unitrack?

I've used the search to see if this has been discussed but didn't find anything. I hope I'm not repeating topics especially since I'm new. The two questions I have are; 1) What exactly is coded track? What do all those numbers mean and what is the best track to get (that last part might be a...