I'm in a mission where I have to go to a designated green area, which is inside a sand dune. I've killed all aliens but do not get a whilte movement square to get to green area inside sand dune.

Ouch, nasty one! Hopefully the first patch will address this (and a FEW other bugs ).

There's a very big bug with the camera angles. Certain camera angles will not let the white movement square show. I managed to get a good camera angle that alowed me to go to the designated area.

However, I am now in a mission with a sub-basement floor that I cannot explore due to the camera. I cannot view anything past the areaof the stairs.

I can now better explain the bug. The camera bounces away if you're underground, such a bunker or sub-basement. A work around is to use the level bars next to the LOS button. Click on the bottommost level bar and the camera will focus on that level without bouncing away.

You'll find on later missions where the level bars say there's only two levels (and technically there are) but you can still move the camera "up" with the arrows to get a better view.

I think the best way to explain it is that the bars indicate how many physical levels there are, but the arrows can go a little higher or lower on occasions to help out a bit.