Hi Gumbi and welcome to the forum!

Yes this has been discussed already, and afaik there aren't plans to implement a free cam rotation. The maps are also designed for the "isoview" so that they are playable without having much troubles with those things you mentioned.
And for myself (as an experienced player) you get around those little things the more you play. Actually I can very well feel if I can shoot over objects (i.e. rocks) or not, you get the feeling after a while.
For the terrain height you can use the isolines to know if the terrain is higher (white isolines) or lower (black isolines) (I don't use them at all but they can be pretty handy).
And try not to climb a hill in an open area, use cover on your way if possible, or just use another path, if you don't want to die.
For the part behind buildings, if you shoot at a soldier which is, like you, in the "hidden" along the wall, you may point your crosshair at the end of the house since if you point at the soldier directly, who is "hidden", you will aim at the roof.
For myself, the only trouble I sometime have is to climb ladder behind buildings, I sometimes indeed have to try it a few times. Maybe enlarging the ladder-climb trigger area could be a nice thing indeed, hmm.
As I said, being able to handle those things makes the difference between skilled and not so skilled players and I don't see them as an issue.