The anodised black hub was introduced in late 2012 or early 2013, so it looks like yours was changed later, particularly if you have Copperslip anti seize on the threads. The black hub spaces the drive sprocket out from the tyre a few more mm and should allow the fitment of a drive sprocket with both inner and outer guide plates as the belt should run fully on the sprocket. With the earlier aluminium hub the belt ran a few mm off the outer side of the hub. Hopefully you replaced the rear hub bearings while the wheel was out as well? They are not expensive and the originals are not top quality.
The steel sprocket is easy to identify, it weighs much more than the alloy one and doesn't wear out, as I am sure you know. The SuperMax should work well, with or without an outer guide plate, several people on this forum have them. The Kumho is a good choice, I have used the KH27 and it's OK. There are some other tyres with improved wet performance and a fairly symmetrical tread.
As you have a 2012 car that doesn't have all the upgrades, have you read the notice from MMC 3rd from the top on this forum about chassis cracks and brake pedal failures?
