#2
@ 0:32 it`s nice that you let all the notes ring, as again on 1:12, and here the bass-notes are getting interesting.
But because it are bassnotes with one note all the time maybe it should have more unexpcted notes. If the main riff is a 4-chord progression maybe it should be more like the 4th measure. The bass-note is more original and stands out between the rest in the last measure. @ 0:16 you could make it more interesting by changing the high notes. Not just one but a bit a melody. It kills the monotonioussness (it`s not a word... I know) and it could change the song. It can also kill the song. Try and you`ll see...
#4
Pretty cool - add a lead and tidy up the little fumbles and it'll be awesome. Weirdly enough it sounded less repetitive second time around (I listened to it twice - first time seemed a bit monotonous, second time didn't ), but a lead part would add interest anyway.