Not sure, all US flights should arrive into F gates actually which is generally a far shorter walk, but I only do these US-CAN flights about four times a year so am not the expert. I don't think I've ever taken a bus at YYZ but again I don't do daily flights like some.

Make sure you have your eTA if on a NZ passport! And dump all fruit and veg so you don't have to declare anything as that is the one thing that got me personally sent to secondary (batting a good average as I've done it at least four other times without issues).