Your Focke Wulf will be tricky to trim for a few reasons. Firstly it will end up being quite heavy, mainly because of the huge noseweight you will need, to take the place of the huge engine that should be there. Thus will make the whole model heavy, and so to keep in the air it will need to fly fast, (just like the real thing) so things are so much more sensitive.
Second the tail surfaces are relatively small, they are even smaller on the real thing
The low wing layout means that it is unstable ( but manoeuvrable). Obviously the real thing had to be, if you had a Spitfire chasing after you! This is because there is little to no restoring moment to bring the wings back level. As the centre of gravity is around the same position of the wings. On the 180 (or any other high winger for that matter) the c of g is lower than the wings, so the aircraft effectively "hangs" from the wings which is obviously more stable.
The way to think about it is that if the real thing is slow and steady, your model will be, and slow and steady is much better for free flight.
Compare the Spit and Cessna in the following videos, notice the difference in speed........
http://www.youtube.com/watch?v=PVq1oFAf ... brfhNSXbiQ
http://www.youtube.com/watch?v=ZhSddWdY ... brfhNSXbiQ
I don't think that the 180 is tricky to build when compared to the 500 series warbirds, just different. If you build it straight and as light as you can it will fly.
I used 3/16" rubber in both the 180 and cub, the last couple of posts in the 180 thread show knotting it etc.....
Andrew