i) The width of the sorting + merging circuit is equivalent to maximum number of devices needed in a phase is O(n/2). As in the above diagram maximum number of devices for a given phase is 4 that is 8/2 or n/2. 

ii) The circuit comprises two sorting circuits for sorting sequences of length n/2 and afterwards one merging circuit for merging of two sorted sub sequences (see phase 4^th  in above figure). Let functions T_m and T_s signify the time complexity of merging and sorting in terms of its depth.

The Ts can be calculated as follows:  

               Ts (n) =Ts (n/2) + Tm (n/2) 

               Ts (n) =Ts (n/2) + log (n/2), 

 Therefore, Ts (n) is equal to O (log² n).

Figure: Sorting + Merging Circuit