Argentinian striker Higuain, 25, is on the verge of signing a five-year contract at the Stadio San Paolo for a reported 40million euro (£34.5million) fee while Liverpool goalkeeper Jose Reina, 30, prepares to reunite with his former Reds manager on a season-long loan deal.
The duo passed medicals at the Villa Stuart sport clinic in Rome on Wednesday afternoon and, according to Napoli president Aurelio De Laurentiis, will be presented to fans at "a big party" ahead of a friendly match against Galatasaray on Monday night.
Benitez knows Reina well, having brought the Spain international to Anfield from Villarreal in 2005, but he is particularly excited to work with Higuain, who has scored 107 league goals in six seasons with Real Madrid.
Benitez told the Corriere dello Sport: "We were looking for a quality player. We were looking for someone playing at the highest level.
"We have signed a player who comes from Real Madrid and we have signed a striker who has scored a hatful of goals and who will adapt very well to our system - an attacking system. We needed a player like this.
"We are all working together to ensure the players we want arrive. We have to sign players who will do well for Napoli for the next three or four years."
Benitez, who succeeded Walter Mazzarri at the San Paolo in June, has already signed winger Dries Mertens from PSV Eindhoven and both forward Jose Callejon and defender Raul Albiol from Real Madrid.
Last year's Serie A runners-up are rebuilding for both a title challenge and a Champions League campaign, and the recent flurry of transfer activity has been sparked by the arrival of the 64million euros (£55million) earned from striker Edinson Cavani's transfer to Paris Saint-Germain.
"Players who come from clubs like Real, PSV and Liverpool can only do us good," Benitez said.
"We have a great squad already, Mazzarri did great work, but we can move forward. For Napoli these signings represent a quantum leap."
Should the moves go through, Higuain and Reina could appear for Napoli against Arsenal in next month's Emirates Cup.
The pre-season event is being hosted by the Gunners, who had been strongly linked with a move for the Argentinian this summer, on the weekend of August 3-4.
Higuain declared his intention to leave the Santiago Bernabeu towards the end of the 2012-13 season, while Reina's chances of first-team football at Anfield appeared increasingly limited following the arrival of Simon Mignolet from Sunderland.
On Wednesday night Reina took to his official Twitter account to say goodbye to Reds fans.
He wrote: "Thank you all for your messages... in the next few days I will be able to bid you a proper farewell."