I'm a newbie myself, so can't advise on the tyre inflation kit
One thing I have found handy is a multi-tool thingo I got from the local Magnet Mart. Its made by Bahco and has the serial number bke850901 written on it. The tool has:
2,2.5,3,4,5,6 &8mm allen keys
phillips and flat screw driver, 1/4 inch square drive, 8,9 &10 mm sockets. 9,13 and 14 mm spanners. It is well made, fits most stuff on a Duke, and fits in the palm of your hand.
I think its supposed to be made for pushies, but it works just fine on real bikes too. Comes in its own little nylon pouch as well, and cost me $20. Its the best all-rounder I have seen. Most of the other multi tools for bikes are from the US, and don't have the sort of stuff you need for a Duke, like metric sockets and allen keys etc. Cheers, ducsport