The trick to fighting in an A5, is that the vert is good, and most people don't expect you to turn fight. Its also very easy to do quick reversals in, due to its high roll rate. My best suggestion is if you need to turn, thing about how to preserve 'e', ie, don't flat turn, do a low or high yo-yo to cut the other guys turn and go for the kill. Also the A5, if you throttle off near the stall is quite nice to get into a rolling/vert scissors with.
Flying the 190s may not be as 'rewarding' as flying a spit 16, but after some time, you will become a much better pilot and understand how to manage 'e' much better. Also, its a great plane to master the most important aspect of air combat, out of plane ACMs. Displacement rolls are so under used and under utilized, yet they are key to getting crossing shots and turning with tighter turning planes while preserving some 'e'.
Its easy to think, hes going there, so I'm gonna pull back as hard as I can to get there by following him, but much more important to think his nose will be there at time 'x', what move can I make to get my nose there in 'x-1' to have enough lead to take the shot, and enough 'e' to continue (hint-hint, displacement rolls).