I eventually saw that indicator, I have to say it's pretty small. Popup saying that you have unclaimed bounties sounds good, also maybe make the button a little bigger, pulsating maybe, and in gold color?
Discarding at 0 happens all the time actually. There's an issue with selecting a tile after its been replaced, but you can put it on board and then put it back to your hand to be able to select it and discard it.
Bounty to have words spelled backwards is great too, got points for GALS and SLAG. After playing a little more I think I was already trained to look for specific combinations of letters. 'Q' is annoying, since you always need 'U' after it, but the points value keeps me holding it until I have a correct setup. Also I had a bad start with no vowels. Maybe initial hand should be semi-randomized to have at least one.
I was playing in browser btw.