Thanks for playing!
To address your feedback points:
There is an indicator, the flames along the screen that indicates an enemy close by out of sight. Could be that it almost always is lit up though, then it doesn't help much I guess 😀
There's a hidden heal if you want to give it another shot: slam them into a wall, grab and kick them into a train. That gives lots of healing!
Your feedback is still totally valid though, because even if these concerns were addressed, they were not well enough communicated to the player.