There is a lot of information about gliders in the gliderpedia section (link above). You need to make sure you are giving them a good diet with a staple food plus their fruits and veggies.
For toys, you want to steer clear of things with string or little pieces they can put in their mouth. Any kind of string poses strangulation and amputation hazards. They are like little toddlers so think of things you could give a baby. I actually buy baby toys for mine.
As for playtime, maybe you need to take them into a small area, like a bathroom that's glider proofed (closed toilet lid, closed drains, all chemical/soap put up) and just sit in there while they investigate. Don;t wear a hoodie or anything that allows them to hide. I'd even take the pouch and sit on it so they can't just climb back in. At first they will be scared, but take in some treats and start coaxing them to interact with you.
Wow, I can't believe you friend found them in a rental house. That makes me so sad for them. But at least it sounds like they have someone who is going to be a better provider for them now.