On auto cast:
The icon only shows if it's a queued action, in this case, the cast is the current action, as that as soon as it is "pressed" it is the "next" event to happen, so it was never queued and therefore never show. The icon would show up, for example, if you had tobi is p1, hinata is p2 and you had a p2 skill (of higher init) queued, once tobi does his thing, hinata will be QUEUED awaiting your p2 skill and have the icon.

It's not just in survival, if you use auto to cast ASAP on certain types of extra chakra gain, this can happen, whereas manual cast usually queue the action because delays causes the newly cast skill to be cast in the middle of another action, which have to finish before any mystery is cast, auto can cast the skill perfectly ASAP. This works, for example, if you had GNW tenten, sage naruto and sage jiraya, if you put game on auto, GNW tenten will be uninterruptable with its turn 1 cast.

So yes, there are times when you WANT the game to be on auto, there ARE advantages.