So when I'm moving around using WASD keys, when I stop moving sometimes my characters will do weird things like take steps backwards or sometimes spin around for no reason, is this sort of thing normal? I haven't found anything related to this and was wondering if there was a way to "fix" this.

I have this problem, and let me tell you, it's a royal pain on the character camera mode. My character will sometimes turn for no reason, often rotating the camera!
I have noticed that the character mostly rotates if I'm holding down both a forward and side movement key (like W and A), then release them at about the same time. So release the side key first, then the forward key. Or, hold the mouse button (left or middle, I think) for movement to stay forced facing one way. That's my preference, since you can use it to look all around, too.
That's all I have figured out to do! Good luck.

In my experience with the game, this is a common problem that I never found a fix for. Indeed, it seems like the entire interface was designed around more of a point-and-click use case scenario instead of actually using WASD for movement. This problem can be highlighted by repeatedly tapping a movement key at a regular interval - get the rhythm right and the character movement is a bit ridiculous.

I ended up just switching over to using point-and-click movement instead of WASD keys, as I found it to be infinitely more precise, and it avoided the majority (but not all) of the camera issues you mentioned.