Those are both great suggestions and are both issues I'd run into when playtesting it with friends.
I tried to indicate where you "click" by making that part of the player's pointer finger slightly darker but some visual effects like you mentioned would be way better and more noticeable.
Since people didn't notice the upgrades screen I have it so that the arrow to open the upgrade screen starts to flash green if you haven't opened it after 90 seconds to let you know it's there. Again great suggestion though, it would be more noticeable and also more user friendly if it flashed or changed colour whenever you can buy something.
Thanks for the great feedback!