Oooh
at tiny baby guinea-pigs (our piglet was 6 weeks when he came to live with us, DD was amazed how light and tiny he was)
They are like little mice almost aren't they.
You can give baby pigs (but not adults unless they are pg/nursing) alfafa hay, it has higher nutrients but it's optional (our piglet hoovered it up, I had to sternly warn out adult away)
They love boxes and tunnels to play in.
With boxes, make sure there's no sticky tape or staples. You should cut two doors to make sure one pig doesn't trap the other.
Tunnels - you can get plastic ribby ones from Pets at Home or online; or the cardboard hay covered tunnels.
Paper bags (cut the handles off though)
I have a shredder specially for my boys- any GPsafe paper gets shredded (cross cut confetti sized) to play or sleep in (especially getting to warmer weather when they have less hay- I only give eating hay changed daily in summer, not to sleep in )
It's nice to vary the toys (and confuses them which keeps them active) 
When you do put them out in the garden make sure your run is foxproof and secure (level surface, and we use metal tentpegs all round to secure)
And only brief grazing at first - 30 minutes then an hour, build up gradually.
Lots of food threads and potential threats (weeds you need to be aware of)
DD and I were looking at some baby pigs today about 8 weeks. She was a bit Pig Broody I reckon.
Get a few old towels for when you cuddle them, they are quick, they wee at first but that improves with age , and their claws are sharp.
Enjoy 