Welcome & congratulations!
First question, yes it's normal. Some of it feels pretty good, then they start scraping, and then it hurts, lol. Grooming
helps bonding though.
Second question, some gliders do fine on their own, but I think for the most part more are happier with a mate than not. Barking is also not that abnormal, but being he just lost his mate recently, he could be missing his buddy.
Bonding suggestions:
During the day, take him out while he's in his sleeping pouch and hold the pouch. Use your hands to hold and rub/caress him from outside the pouch and talk quietly. Have a treat handy for when he pops his head out. At that time, give him the treat and try petting his head. After some time of doing this and he's taking it well, try placing your hand into his sleeping pouch (fist form) very slowly. Let your fist be next to him then gradually work your way into petting him, the progress to the point of cupping him in your hand if you can.
If at any time he is not liking what you're doing, back off a step or two and build again more slowly.
After you established some sense of trust, try out of cage play time to firm up your relationship.