Yes, the straight stock is common. On a shooter you may prefer a C stock. Are there any cartouches on your stock? There are also 'scant' stocks which were an attempt to make C type stocks out of straight stock blanks
The brass hardware is pre-WWII
This is a good (if slightly haphazardly arranged) link for info on these bayonets
http://www.usmilitaryknives.com/bayonet_points.htm
The M1 bayonet is a deceptive name. It isn't designed "for" the M1 rifle specifically. It's just a name, like M1 helmet. The M1 rifle was simply designed to take the same type of knife bayonet that the 03 could take. The stacking swivels on the 03A3 and M1 are at nearly the same height, too- they can be stacked together
The Model of 1905 on the M1 pictured fits the same for the 03A3 to it's left
