Police seized $6 million of luxury cars - including 15 Mercedes-Benz, a pink 1959 Cadillac and a Rolls-Royce Phantom - and $10 million from financial institutions during Friday's raid.
Also arrested were Bram van der Kolk, 29, who is from the Netherlands but is a New Zealand resident, and Finn Batato, 38, and Mathias Ortmann, 40, both from Germany.
The four men are due to reappear in the North Shore District Court today for a hearing to decide whether they will be granted bail.
The FBI is seeking to extradite them to the United States to face charges of conspiring to commit racketeering, conspiring to commit money laundering, copyright infringement and aiding and abetting copyright infringement.
The website was shut down by the FBI, sparking a furious reaction from hackers who retaliated against a number of US government, recording and movie industry sites.
Dotcom, who is a native German, received residency in New Zealand despite declaring two convictions, which he said had been wiped by "clean slate" legislation in his home country.
Officials originally approved his purchase of a $30 million Coatesville mansion, saying enough time had passed. However, they later decided he did not meet the "good character" test to buy land here and the sale was blocked.
Instead, he has a long-term lease on the property, which is owned by a company directed by Chrisco founder Richard Bradley.
A source told the Herald Dotcom ordered about $4 million of renovations at the mansion after moving in.
"I know the whole place quite well, I did quite a bit of work on the renovations," said the source, who spoke on the condition of anonymity.
"It's insane, and it gets more insane inside. When we were there we called it 'extreme home makeover, millionaire edition'."
He said Dotcom's master suite had a television at the foot of the bed believed to be the biggest in New Zealand. Off that room was an ensuite and a dressing room.
A heated lap pool is just off the master ensuite, boasting underwater speakers, imported spring water and a custom ladder worth around $15,000.
A graffiti-style painting depicting Dotcom and his wife, Mona, sat on the wall of one room, which was fitted with about seven 60-inch television screens - each with its own X-box and Lazyboy.
A number of oversized cartoon-like heads were placed on other walls.
Dotcom was not at the mansion while the work was done and most of the team never met him.
"He is very anonymous. Not many people met him. Most of his stuff is all done through someone else. When we were there the guy who designed the house and the architects were living there, everything was done through them."
He said the garage, home to Dotcom's collection of cars, was known as "the barn" and had a glass-tiled floor. His children had their own quarters on the end of the building, looking out over the sprawling grounds with a view of a sculpture of a rhino.
During the renovation process security was tight and workers were watched closely to ensure no details got out, the source said.
A "fun documentary" titled "Kimble Does Monaco" gives even more insight into Dotcom's "crazy" life. The footage shows Dotcom and his team - including Batato and Ortmann - on a trip to Monaco in 2006.
Dotcom, referred to as "King Kim", takes the group on board the 80m superyacht Golden Odyssey for a flashy party.
At a second party Dotcom is surrounded by topless and scantily clad women being sprayed with champagne by male guests. He drinks straight from a punchbowl, plays poker and lashes a man's bare behind with a leather belt.
"Fast cars, hot girls, superyachts and amazing parties. Decadence rules," said the blurb accompanying the documentary, which Dotcom dedicated to "all my fans". In the credits he thanked his "mama" and "psychiater" - German for psychiatrist.
