yep. fourstar is a tail dragger. and while i've not flown it myself, i've heard it is a great second plane.

the 70 fourstroke is the right size for a 46 two-stroke plane. 60 two-stroke size planes fly with a 90 fourstroke.

i would recommend you take a look at the World Models Supersport 40. it's still a trike and very very good second airplane. the Rambler 30 is my favorite plane and also a good second plane. the FXi engine would be a little big for it but not too bad. and last but definitely not least is the Kyosho Calmato Sports (pictured), which is not only pretty but flies well.

as for mastering the trainer. it's unreasonable to be able to do a rolling circle and a continuous roll without losing altitude with a trainer. i dont' know anyone that can do a rolling circle with a flat-bottom wing trainer without slight variations in altitude. these things are much better learned on an aerobatic plane. and i don't know anyone that has NEVER been disoriented provided they are not beginners. you should, however, be able to also know the orientation of the plane through the inputs you put in so that you are depending on seeing the plane clearly to control it.

as for feeling comfortable, its very important... but its equally important that you really do fly well. i would still seek some opinions from club members to see if they think you're ready. i would also suggest that you have someone buddy box you a few times in the beginning. i know far too many people that fly planes well beyond their means that become hazards at the field.