The algorithm we used is quite similar to what George shows in one of his earlier AUMs, so one way to get you started would be to read and test it (this shows just how much has George helped the community).

It just takes a lot of testing and tweaking to get the results you want but it's not that difficult. Compute the path over several frames to reduce it's impact on fps, check for all the cases when it behaves else than expected and solve them one after another till you're satisfied

The nodes we used for the pathfinder to work had to be placed manualy but I just could not find any other reliable way to achieve this.

I don't check A6 forums as frequently as I used to but I believe that Larry Laffer did some excelent job when it comes to pathfinding - far better I think than what we did. You should definitely check his posts.