I'd leave the straw out for young pigs ( you aren't really meant to use straw, but I use really soft barley straw in winter at the back of the haybox, just to bulk and insulate, they don't eat it. ) Stick with hay for now.They like to sleep and eat in it, mine CBA walking all that way to a hayrack.
Newspaper , shredded paper, Megazorb if you want absorbancy but sawdust and shavings aren't suitable for their respiration .
Give them a house each - a box with no staples or tape, cut 2 doors so they can't trap each other.You can use the igloo and a cardboard box -easy to throw away.
We have 2 boars (a 3.6yo and his newer cagemate 10 months old. The brother died last year so the new one came to live with us at 6 weeks.
They have the most amazing capacity to pee
and pooh
so bag all the newspaper you can (take out any staples) .
I've been through every concievable bedding- fleece, Megazorb, towels,
What works for mine - rubber car mats (one of those boot liners, brilliant) insulating and waterproof but out of the reach of tiny teeth cardboard and those wooden cat pellets that are small animal safe.
Newspaper and hay.
Have you got an outdoor run?
They love those plastic tunnels to run through.
Roll up the paper + hay every day/2 days depending on how manky they are, then weekly replace the cardboard/pellets.
Boars are lovely, cuddly, noisy, greedy, messy little creatures.
But be aware, you're going to ride the storm of the Terrible Teens.
Give them space,
Somewhere to escape from their cagemate (boars aren't in each others company like sows but they like to know the other one is there)
Enough room between food bowls and water
Enough food to avoid squabbles.
And - protect them.
Draughts, damp, cats, extremes of heat/cold and foxes.
Don't underestimate foxes 
Enjoy them. 