how to do first person animations?

alright, i've received tons of good answers from googling things and asking here, so i'll continue.

recently, i've been trying to create some first person animations for fun and to challenge myself, similar to the likes of phantom forces. i'd like to just say now that im well aware that i'll probably never reach the level of phantom forces animations, and im not trying to either. just trying to create some dope animations.

anyway, i have these fake arms that i've welded to the player's head, and i use a local script to rotate the head based on mouse movement up and down so that the arms rotate and point with the camera. my problem is that there is only so much you can do with some blocky fake arms welded to the head. how in the world do people make such fluid animations? i assume that most animation creators use inverse kinematics to control the arms, and simply calculate and change an end point, which would allow the arms to point and move smoothly. is this true? is there another way i should go about doing it?

even if so, im completely lost as to how to make the animations react with physics, for example, when you move your camera, the arms/weapon sways a bit, depending on how fast you moved it. any ideas?