Hey lostwords:
After reading your reply, i think your ideas were spot on - maybe just a bit more in game explaining to show what each thing was for. I like your idea for taking out the power ups for the first couple of levels of they are confusing. Maybe just remove the icons all together and then add them back when you want to introduce the mechanic so the player isn't confused about what they don't do. I actually do think the high tide idea is pretty funny and i think it is a great mechanic for Scrabble. An idea could be a short popup / cutscene that shows a text box that says "High Tide" with the waves going very large across the screen - then after that cutscene finishes, drop the waves all the way down to the bottom of the screen so you can still see them but they arent blocking anything. I'm kinda thinking like 5-10% of the screen size.
Just some ideas...
Cheers,
Daragard