Javascript (E6) 174
==

138 Logic, 36 I/O 

    F=(x,y,d,m,D='NESW')=>(d=D.search(d),[...m].map(s=>({M:_=>(y-=[-1,0,1,0][d],x-=[0,-1,0,1][d]),R:_=>d+=1,L:_=>d+=3}[s](d%=4))),[x,y,D[d]]);
    p=prompt,p(F(...p().split(','),p()))

**Test**
Test in javascript console in Firefox. It's simpler to test the function F avoiding the popups.

    F(1,2,'N','MRMLM')

Output

    [ 2, 4, "N" ]