There are just two questions - the first is universal, the second more specific.
Can he succeed as a full-time head coach? Plenty of eminently capable men have sat in the AFL's hottest seat and been found badly wanting.
And can he unite Essendon, winning over or at least nullifying the vocal faction that wanted his great friend James Hird to have the job?
Certainly, if he successfully answers question one, then that will go a long way to solving question two. But at least in the short term, the second issue is bound to bedevil the man known as Spike.
Club president and fellow former player Andrew Welsh is adamant they have their man. Through Tuesday morning's media conference, Welsh raved about McVeigh's credentials.
Welsh also hailed McVeigh as the ideal force to lead their "one club" ethos and reunite the fractured, broken Bombers.
McVeigh played 232 games for Essendon from 1999-2012 and was there when they were consistently an AFL powerhouse. He knows what it means - how good it feels - when the Bombers are arrogant and flying.
The end of his playing career was also marked by tragedy and challenge. Brother Jarrad, an AFL player at Sydney, lost his daughter Luella barely after a month after she was born in 2011.
One of the defining moments of the Swans' 2012 premiership was Jarrad and wife Clementine celebrating with second child Lolita-Luella. Mark wrapped his brother in a massive hug, a few minutes after the final siren.
When Mark was at Essendon in 2011-12, he was one of the players involved in their disastrous drugs program - a debacle that continues to traumatise the Bombers. The scandal and its ongoing fallout has fuelled the push to bring back Hird as senior coach.
McVeigh retired in 2012 but was still among the 34 players to serve anti-doping suspensions in 2016, when he was barred from working as an assistant coach at GWS.
In 2022 he became the Giants' interim senior coach when Leon Cameron left, with Hird serving as one of McVeigh's deputies.
Eventually, Adam Kingsley took over and McVeigh left for an assistant coaching role across town at the Swans.
Just when McVeigh probably thought he had seen everything, the end of his tenure at Sydney was marred by the scandal involving five players last week in a Melbourne hotel room.
He will go into the Essendon job with eyes wide open about AFL life.
McVeigh has made it clear from the start that he is a hard taskmaster. The players are on notice that they had better turn up to pre-season training, ready to go.
But no-one will work harder than McVeigh.
"I'm a no-ego coach ... I (lived) an hour-and-a-half north of Sydney, so the challenge of getting to work was really difficult, leaving at 4am every day for the last 14-15 years, working big hours to get my craft right," he said.
"I've rounded it out, I haven't just coached at senior level. I've gone back to academy level, I've gone back to under-18s.
"So the spectrum of coaching is far and wide."
McVeigh was asked how grumpy he will be as a coach. He referenced the famed strong personality of St Kilda coach Ross Lyon.
"I'm not grumpy, am I girls?" he laughed to his daughters.
"What I love to do is be around people and I love to be able to delegate to people who have great experience in certain areas.
"I don't know everything. I've never thought that.
"I think I'm someone who is genuine, I'm a happy person, I love working really hard, I love a laugh and I love looking after my people. So I don't think I will be Ross Lyon."
Just as McVeigh has to answer two critical questions about his coaching capabilities, similarly, there were two contrasting messages during Tuesday's media conference that McVeigh and the Bombers need to manage.
The first was that this is not about nostalgia, but looking forward. They haven't just gone with an Essendon favourite son for the sake of it.
Yet one of McVeigh's very first comments as coach was to note that his parents first walked him through the door at Essendon when he was 17, and they were there again when he returned on Tuesday, aged 45.
It's a complicated way ahead, with so many potential pitfalls.
And as of Tuesday, August 25, it's 8024 days since Essendon won a final.
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