You will not need a buddy box.

I went from an LT-40 (about 100 flights) to a 4*40 two summers ago. For the first flight have someone experienced take off, trim it and set appropriate rates for you. Then have them hand you the box a few mistakes high. The 4* will be very fast and responsive compared to the trainer which will take a little getting used to. But if you pull the throttle way back and slow it down you should find it very forgiving and easy to fly, just like the trainer. Landings won't feel much different than the trainer- I found landing my 4* actually easier than the LT-40.

Since this will be your first tail-dragger you will need some coaching on take-offs but you should get the hang of it pretty fast.

When you begin to feel comfortable with the plane then open up the throttle, hang on and have fun! You will find that you don't need to use rudder to fly a 4*, but as you learn new tricks you will find yourself using it for snap rolls, spins and the like.