Oh so this is pretty much what it's doing:
1) When going from R to 1st, if there's resistance, it will go into 2nd instead after a few additional seconds (assuming no paddles are pressed again, if you keep pressing the paddle it sort of goes into a loop).
2) When going from 1st to R, it may go into N instead... that's just because of resistance felt. This time, you have to click the paddle again to go into the correct gear. This is normal too as the action of it going into N, then going into R would reset the syncros allowing for smoother engagement on the next attempt to go into 1st.
3) Finally but not specified here is when it will go to 2nd from N if it feels resistance going into 1st. This is part of some other tech spec I read and indeed does do it after a few additional seconds. I've put about 4k on my car 4 years and I'd say this has happened about 4 times after coming to a stop and going into N.
PS, all these (esp #2) would align with scenario 2 that you mentioned of only getting into 1st after going into R first. Doesn't mean anything is wrong and this is exactly how a manual car "feels" sometimes. It just won't slip into 1st easily, so you have to change gear, go into N, go into 2nd or 4th or whatever, just move it a little more forward or backward, then it goes into R or 1st just fine. Doesn't happen often, but on my other gated cars, does happen every blue moon (BMWs, Porsches, etc).
EDIT: oh, it also explains here when the egear might go into N (in the box on the lower right).