Hi niko - also in v2 one other possibility for drawing at a certain height in the 3D view only is to set your construction plane to that height. Then after that any points that are picked freely rather than object snapped will be on that adjusted plane.

But generally the way things are set up that if you want a 2D curve result, switch to draw it in one of the 2D views and all the stuff like planarity through the first point and object snap projections are all enabled when you are working in that view.

- Michael