I'll answer some of your questions,
1) I belive it is both, with the 22M cylinder installed it shoots .22M Ammo, with the 22LR cylinder installes it shoots 22LR. All of these "convertable" revolvers that I have seen used the same barrel even though there is a slight difference in the bullet diameter of the 2 cartridges. As I recall, it is "barreled" for the 22LR ammo and the accuracy of the 22Mag suffers. It appears that you have the 22M cylinder.
2) I am not sure here, see answer 1).
3) No, it's just missing in your pistol.
4) Not my expertise.