Chi squared test questions

As part of a small study, I’ve have put together a table with results from a population of individuals stratified by age. For each line, I would like to perform a comparison between a variable and the groups. For this I’ve chosen the Chi-Squared test for independence (I’m using graphpad prism to calculate the tests)

Question 1: Is the Chi-squared test the most appropriate test for this type of data representation?

Question 2: Is my interpretation (below) of each row’s p value correct?

• Row 1 (p=NS; prior symptoms vs group): variables are independent thus no relationship
• Row 2 (p=0.007; prior test vs group): variables are dependent with a relationship between variables (those between age 20-60 more likely to have been tested).

Question 3: row 3 contains 2 groups with zeros in them making it problematic for the Chi-Squared test. Due to it being 4×2, Graphpad Prism will not let me use the Fisher test. What would be most appropriate here? Should I just put a blank space instead of a p value?

Look forward to your thoughts.