An auditorium has 12 rows of seats arranged so that the number of seats in each successive row forms an arithmetic progression. The first row has 28 seats and the last row has 83 seats.
(i) Identify the first term and the last term of the progression represented by the rows of seats.
(ii) Calculate the total number of seats in all 12 rows.
(iii) A 13th row is added following the same pattern. Determine the number of seats in the 13th row and find the new total number of seats in the auditorium.