Did someone call for the Tang Police?
As you have already heard, no matter what the fish store lady told you a blue tang, no matter how small it is, is not suitable for a 10 gallon tank. It is not the size so much as the swimming room they need. I realize you want to fish (they are cute) but please think of the fish - it would be like putting you in a closet and telling you to live in there...
I see you have decided to bring the tang back - kudos to you, I know its hard, but its the right thing to do.
Now for the clownfish... No clown fish should be in anything less than a 20 gallon tank. The vast majority of knowledgeable people say 30 gallons.
Again, I know they are cute, but you have to think about the fish...
Actually as I was reading your post and then seeing your pics, my blood was just boiling...
But then I saw that you were a reasonable person and decided to do the right thing and return the tang, now hopefully you will do the same with the clowns...
There are several small "nano" fish that would do fine in your tank, go to the Drs. site and you will see them.
Here are a few cute ones
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