next to plaza nueva there are "carpas" or tents set up as displays showcasing different products. i cant guarantee this will be there the exact day you are in sevilla. i can tell u that there are many ceramics shops in sevilla all throught "las calles de salon" or the old quarter streets. these are many but a few that come to mind off the top of my head are c/sierpes, c/bailen, c/cuna, plaza del duque, all the streets that come out of plz salvador, etc.
they are full of shops. they sell feria dresses, fashion boutiques, pottery, shoes..etc. its good to just stroll from street to street and find what you like. you have aloooot of options believe me!
also, i don't know what u like in terms of food but if i can recommend one of my fav "cheap eats" that i've been going to since i was a liitle kid..its called: el patio de san eloy..its very cheap, fresh and delicious!! its full of uni students so u know the prices can't be beat el patio de san eloy