The Mills debate - I agree with the consensus here, if he plays, he's a guy who has to open the bowling and probably bowl six of his ten overs in that first spell in the lead up to the 14th where Nathan McCullum can be used, if he does bowl his full ten, it should be before the 35th over before the powerplay and death stages start.
Southee should probably bowl in lots of four, two and either another two sets of two, or four at the end - four overs at the start, two overs during the powerplay, four overs during the end. I'd rate McCullum to bowl three of the five overs during the powerplay which means we're looking for someone to shoulder the other lot of overs with Southee from the 42nd until the 50th. McCleneghan isn't a bad option here, he attacks and generally takes wickets when players are going after him. I think Anderson has shown the potential for being a very good bowler at the death, good variations, change of pace, can hit a difficult length and seems to have great composure.
The real wonder for me is why we haven't seen at least ten overs combined from Williamson and Ryder, Ryder's nagging medium pace with his variations has always been pretty effective for NZ and he's shown that he's quite serviceable in the leg side around the wicket line that our spinners have started to bowl too.