Working with Herath would benefit Ajaz Patel, Mitchell Santner and Rachin Ravindra, said Stead.
Oram will commence the role vacated by Shane Jurgensen towards the end of last year on October 7, with New Zealand's three-match ICC World Test Championship series in India the first assignment for the 46-year-old.
Latham spoke to reporters on Wednesday as New Zealand Cricket released its summer schedule, which starts with a three-test series against England in November before white-ball series against Sri Lanka and Pakistan.
Williamson's decision marks the end of an era for a New Zealand team which made the semi-finals of the previous three T20 World Cups and the 2021 final but ultimately missed out on a maiden white-ball title.
Having made at least the semi-finals of the last three editions, New Zealand crashed out in the opening round this time.
Stead, who took over as New Zealand coach in 2018 and led them to the 2021 final, has a year left on his contract.
The 37-year-old lefthander's last international was a T20 match against India in 2020 -- but he had long hoped to claw his way back into the squad.
Kane Williamson will captain the T20 World Cup squad for a fourth time as New Zealand hunt for a maiden title after reaching the semi-finals of the last three tournaments and the final in 2021.
New Zealand all-rounder Rachin Ravindra became the youngest player to win the Sir Richard Hadlee Medal, the highest award for men's cricket in New Zealand, on Wednesday.
See the best moments of today's matches of the ICC Cricket World Cup 2015 where New Zealand faced Bangladesh and England locked horns with Afghanistan
Who will be on the ball during the next round of matches at the ICC Cricket World Cup 2015 when Bangladesh face New Zealand and England take on Afghanistan?
A sickness bug in the camp and the odd niggle is about as troublesome as the World Cup campaign has been for New Zealand so far
For both these teams a place in the quarter-finals is safe - New Zealand courtesy of a serene run through the tournament and Bangladesh after their seismic victory over England
New Zealand dominate the leading wicket-taker positions at the World Cup. Tim Southee and Trent Boult are tied for top spot on 13 apiece
How will the second week of the ICC Cricket World Cup 2015 treat the various teams hoping to make it to the knock-out stage of this competition?
England's eight-wicket World Cup defeat by New Zealand in Wellington is the most one-sided one-day international between Test-playing nations
See the pictures of an entertaining encounter at Wellington where New Zealand faced England in the ninth match of the ICC Cricket World Cup 2015.
Tim Southee captured seven wickets for only 33 runs in nine overs and reminded the glory days of swing bowling in the late 80s and 90s.
New Zealand trampled England with Tim Southee’s seven-wicket haul and Brendan McCullum’s fiery batting in the ninth match of the World Cup 2015 at Wellington