As to bayonets. There are way too many variations for me to afford to collect. But I did try to get an example for each of my rifles from the Krag to the M16A2.
So from left to right:
Krag 1901 Bayonet
Springfield (and used through WWII on the Garand)
M1 M5a1 Post war Garand bayonet, used in Korea
M1 m4 Carbine
As mention there are dozens of variations and models. The original '03 Springfield was a rod bayonet, but (I believe it was) Teddy Roosevelt vetoed that and went with the knife bayonet.
Odd they went from the rod bayonet of the Single shot Springfield's to the Knife blade on the Krag then back to the rod for the Springfield.
The most "useful" bayonet is the latter M8 (M16a2). It has a wire cutter, knife side and shredded edge for cutting through aircraft frame. Though I think this knife is a bit heavy (I use mine all the time for repairing fences).
Bayonet charges are history, but the bayonet is still quite useful for the soldier. Though I never poked anyone with mine, in Vietnam I used the heck out of my M7, from digging fox holes to toasting pieces of sliced C-rat white bread.
I've also seen the M7 bayonet used on the end of a rifle to aggravate a water buffalo. Not a good idea, the buffalo whipped his butt, and he had to be medivaced.
I like bayonets.