As far as centering the hole:
Take a larger piece of material, say 1" square, and drill it through jus a bit smaller than tap drill. Then drill and ream it for a snug slip over shaft a good 1" to 1 1/2" deep. Slide it on the end of the shaft and run tap drill through into shaft. The longer you can make this slide on drill bushing the straighter it will keep you.
As for hardness of the shaft, if it is case hardened, you have several options for that. If it is thru hardened....they're right it is edm time.
I hate deburring.....
Lets go (insert favorite hobby here)