The way you cut the chicken is important. If you cut the chicken breasts into cubes, it tends to become dry. Slice the chicken on a diagonal angle. This will ensure that the chicken remains moist even after being fried.
This recipe gets its unique flavour primarily from curry leaves. Curry leaves have a very unique flavor/aroma, so there’s no exact substitute for it. You can however, make this chicken without it, but the taste won’t be same of course.