DX-coded and non-coded are the same film materials except that most auto cameras can read DX-coded films and thus, u need not adjust the ISO. it is automatically adjusted to the ISO as reflected on the film catridge.
as for non-DX coded, u'll have to adjust the ISO settings accordingly.
for ur FM2, it matters not whether it is DX-coded or non-coded. u still have to adjust the ISO manually.
ya it can. DX code is just a code using patterns along the side of your film canister to tell the camera wat film you are using. So compact cams can read the speed of the film that is placed in it. for FMs, you have to manually set the film speed. so it doesnt matter.