Generally sustainer style pickups need to be in the neck slot as the string tension is less in this area and it's easier for the pickup to start the string moving.
As for a humcancelling single coil, unfortunately we don't make one.The main reason is I personally think the compromise in tone is too great.Squashing a humbucker, either by stacking 2 coils or having 2 minature coils side by side, never sounds like a real humbucker and also doesn't sound like a single coil either! We do, however, make a very powerful single coil especially for the neck slot which'll work fine-the Trilogy Suite neck. 8)