Good Peter by all means go for your cub You will do fine. I think you said you wanted an ARF and in that case the Hanger Nine eighty incher is among the best flying of the cubs. I have flown and tested a fair number of different cubs for folks and the Hanger nine is one of the best ground handling of the bunch. Delightfully easy to do wheel landings with, Not so with some cubs. I have one that I dug out of the trashcan 5 years ago that has served beautifully on wheels and floats as well as a night float flyer. One of the more enjoyable things to do at dry lake that I visit on occassion is to just fly around my self in a continous circle of say a hundred to a hundred and fifty feet then simply let it settle to a one wheel touch down and keep it rollin wing down on one wheel for a couple of circles then increase power a bit an lift off. Some times I have just done this for a whole flight 'just because'!
Back to the Adverse Yaw thing. Indeed AY affects virtually all aircraft big and little and it can be handled in a number of ways. First off we all should practice using aileron and rudder together most of the time as full scale pilots do but for them it is simpler because they can feel it in flight on the other hand it is not so apparent when we can only depend on our eyes at some distance. Many full scale aircraft do 'cheat' however by two differant mechanical means, Differential aileron and or aileron to rudder mix! Yes all you purist out there many full scale aircraft do in fact use some degree of aileron to rudder mix.
Peter you can visually see the effects of AY on any visit to a flying field. just watch any high wing cabin type or trainer (the type that are most affected) on climb out at the first turn, the airplane will turn ok but nose kinda pointing the wrong way and the airplane seemingly skiding sideways, That is Adverse Yaw. There are Three ways of correcting this if you want to impress the Peanut Gallery in the pits. They are: manually using appropriate rudder imput with aileron at all times, using differential ailerons and finally using electronic aileron to rudder mix. In the real world using a mix of all three methods is probably not a bad idea as most of us do tend to get lazy just like full scale pilots.
Aileron Differential is mearly not allowing the downward moving aileron to go as far as the upward moving one, therefore tending to minimise the additional drag from downward moving one. It can be acheived by the simple rigging trick of the angle your aileron servo output arms are set at neutral or it can be done electronically with a computer radio.
As for you last question your Hitec Flash 5X will electonically provide aileron differential or aileron to rudder mix.
I apologize for being long winded, now get busy and go enjoy that Cub.
John