(ii) First, arrange the 7 cup cakes, which can be done in \(7!\) ways. This creates 8 gaps (including the ends) where the brownies can be placed. Choose 4 out of these 8 gaps to place the brownies, which can be done in \(^8P_4\) ways. Therefore, the total number of arrangements is \(7! \times ^8P_4 = 8467200\).

(iii) Treat the 4 chocolate biscuits as a single unit. This gives us 7 units to arrange: 1 chocolate unit, 6 shortbread biscuits, and 2 gingerbread biscuits. The total arrangements of these units is \(\frac{9!}{6! \times 2!}\), accounting for the identical shortbread and gingerbread biscuits. Therefore, the total number of arrangements is 252.