the pilot has to solo the airplane the first time he or she flies it, since it only has one seat.
Normally, yes. Just like the Czech Z37 'Bumblebee' crop duster with hopper behind pilot. There are some two seaters for training, although rare. Same goes for Pawnee.
Check out
http://www.wvsc.org - I wanted to get couple flights with them when I was very near, but didn't get to, in the end. Maybe next time - it'd be better, with some Blanik experience. That PA-25D caught my eye and stayed in memory.