>Originally I liked the idea, but it in practice I found it to be a hassle.

You are not the only one! There is currently work going on in the development branch "Controls" to adjust the controls (and the interface) a bit. For example, the two-hand-stuff is removed. Also, in the "Controls" branch, you currently throw objects with right-click and use them with left-click.
In the main branch you can throw loam and other tools with Shift+Click.

>In practice it turned out that I memorize the combination for entering the building and do the same combination for exiting - which has no effect anymore.

Mh, so the problem is the default order of the entries? How should they be ordered? I think currently grabbed objects (Lorry) are at the front, so when you let go of the lorry all other entries change the positions and move to the front. I don't know how that could be changed, though. If you have suggestions, please tell :)