First of all, welcome to Minstrel, Sid and Ewok.
Prepare to be their Cavy-Slavey.
I'm not a huge fan of fleece personally , there are pros/cons.
My pigs have always liked hay to sleep in, or in the warmer weather when hay is to insulating , shredded card or Rodent Safe wood litter
I used fleece on the base of a C&C because it was huge , I'd have needed so much covering for it .
You need to wash fleeces in something very bland smelling, guinea-pigs are very respiratory sensitive and their little noses are right near the floor . (I use Ecover liquid) . No fabric conditioner ( it stops it wicking) . Fleece draws / wicks fluid through itself so you have a dry top layer , you do need the absorbant base .
I use layers of puppy pads and newspaper under any bedding (mine don't chew bedding thankfully) you can get the washable bed pads (if you have any toddler bedding, I had HippiChicks from when my DC were little)
And Yes to the wash bags , they will save your sanity an your washing machine
. I shake out the excess hay then put the detergent inside the bag, hang them outside when they're washed and the rest of the hay blows away.
Sows are messy little tykes (far messier than boars IMO)
We did daily bedding changes,(used to have 5 piggies) now we have one old girl she can stretch to 2 days .
Hay gets EVERYWHERE . No matter how careful you are , they bring half the bed out when you lift them, or it gets kicked out , especially if you have a C&C (grid) cage. If you do have C&C you need to line the base . They cannot walk on grids it damages their feet .
If I gave my pigs a folded up fleece or a box of hay , they pick the hay every time . They pee/poo/sleep/eat the hay so it does get manky .
I used a rack for RediGrass , it needs to be high enough hat they don't try to climb in, and not too high that the hay falls in their eyes.
In summer we stuff loo roll tubes with hay to pick at .
For three pigs you'll need a pretty big cage , at least 5'x3' bigger is better. Sows smell more in season, it lasts 24-48 hours and they can go a bit snippy so be aware . Its just a hormone thing, not them, give it time they're back to themselves again.
I love guinea-pigs, my DD and I have kept them sine she was 9yo (she's nearly 17) and I had them from 9-22 myself . We are at the end of our pig cycle now having lost two in the last five months we have one old lady left (haven't attempted a match up , she didn't get on with my other sows ans only tolerated our lovely boar when it was just the two of them)
They are amazing characters, very noisy, messy , greedy
, cuddly -not the sharpest knives in the drawer though !