A cave, the blind are bats.
I am an open-air sale.
Remove two letters and I am a brand.
Change one letter and I am a food item.
Change another letter and I am found at the coast.
Change one final letter and I am a hand signal.
What was I and what did I become?
I say everything, I hear to others around. I'm not an animal, nor part of the human race. I will, immediately, repeat after you; But only if my tail is in place. What am I?