Hello Guineapigquestions
I got an alert from GoodVibes 
Fiest -welcome to the world of guinea-pigs , they ar lovely , chatty, greedy little rodents ( i havent kept piggies for over three years now since our last oldie died, and DH got his wish to have The Cats . He did like the guineas but he's more a cats person)
The advice to get three boars is rubbish advice and worrying that the PetShop is peddling this . When I see some GuineaPigs for sale on Gumtree in tiny cages with no stimulation, I often think the reason for sale is fighting . When they get to the 4-6 month age its Hormone City .
i think the Boar Trio became popular because when one dies , you don't have a single pig . But managing 3 boars is tough .
Most likely they found the males harder to sell too. When I got GP6 the Rescue had just taken in a huge haul of boars . All the piglet sows were reserved .
I would agree they are friendly and huge character , and IME less untdy than sows ( though a guinea-pig can never be accused of being tidy !)
You do need loads of space , and they need hiding spaces but make sure they cannot trap each other . So two exits to a box for example .
Our first bar pair had my DC old playhouse (it was about 6'6"x6'6" floor space) DH built a haybox from an old cabinet that was about 3'x3' and one side open so easy exit/acess.
They whinged this wasn't enough but slept in the haybox but not together (evidence from pooh nests)
The first winter they had the Mother of All Fallouts (I think they went barmy on coriander , some herbs are like guinea-pig crack)
As your piggies are new and likely scared it'll be a while till they show their personalities .
What to do with your 3 boy group though?
There's loads online ( the guineapig forum is a good start )
Do you want to reduce to 2 ? I don't know if I d want to send one back , but there's an overflow in Rescue .
Are you prepared that they might end up in 2 groups ( I had to do this when one one my sows wouldn't bond , we had a 3+2 ) More cleaning and work but kept them safer and they could chat through the bars .
I'd also want to double check the sex. Should be fairly obvious , they'll have obvious balls by now .
With handling , you need to make them feel secure . Easiest is to corall one into an open top box, block them in then scoop. (Easier for adult hands)
One hand under the belly (I always tucked my index finger through the front legs to stop them slipping forward) and the other under the rump to lift .
Cuddle on a towel - piglets have sharp claws ! and they will pee until they can get you to read their signals .
Little and often handling to begin with .
Ours liked being up at our necks
At the moment , they only know each other . They are scared
They will be thinking that you and your child are eagles who are going to swoop down from above and kill them.
They are (sorry guineas but this is harsh but true ) as thick as mince . But its part of their charm.
They are gentle ( I'm not saying they don't bite people but they rarely do and 99.9% of bites are something a human has done wrng )
They can't leap out of the way , or kick hard . They have rodent teeth and it is all testament to them that they don't bite people .
They love food and routine
they need protected from damp , cold , heat , direct sun, draughts
They eat pretty constantly . They need unlimited hay ( guide id a wedge of hay their body size but in reality , unlimited . They eat , sleep and toilet in it )
C&C are good and you can adapt them but they need a liner , guinea pigs cannot walk on mesh
In the garden , they need a secure covered run with no risk of a fox getting them.
Theres toxic plants to look out for . And the risk of bloat if they gorge on fresh grass ( I told you they're greedy)
Ours had the playhouse (which had haybox in and we cou;d remove the windows leaving a protective bars/mesh.chicken wire screen)
C&C and a 4x2 nightcage (depending on who was sharing) for winter nights in the small bedroom
If you come over to Small Pets there's loads of Piggie Advice -food beding etc