Welcome and congrats on being a new suggie parent.
At 7 months your male is capable of mating, you've already addressed getting him neutered but make it an asap item. Take both in for a well check and to make sure your female isn't already pregnant.
It's typical for them to be curious enough to check you out through the cage, especially when you have a treat. As to knowing when they're 'really bonded'...It just comes along slowly until you know their behaviors and mannerisms so well that there is a trust going both ways. After adding a 3rd glider to my girls a couple weeks ago I suddenly realized just how bonded I was with the girls and how much work it took to get there. I had come to take it for granted.
Spending a couple hours with them in a bonding pouch during the day while they are asleep is the best start, other than taking time sitting by the cage and talking to them softly and offering treats like you are doing. Give them some time to get comfortable and settle in their new home first. I talk to them softly while they're in the pouch so that they get used to my voice and movements and associating it with a safe and comfortable situation while they sleep/rest. A more confined place is easier for out of cage time with new gliders rather than a whole room. Some people use a tent, which is great because there is less room for them to go too far and they will be easier for you to get back into their pouch when play time is over. Some people also use a glider proofed bathroom instead of a tent. Be sure that everything that may fall and all personal care products are put away. Wipe up any soap residues. Close the toilet. Check every nook and cranny for any space bigger than a half in that they could squeeze into and block it up.
Don't be dismayed that during out of cage time they typically will be more interested in running around and checking out their surroundings. Day time bonding gives you cuddle time, night play time is for them to get their exercise, etc. Once you have established a comfortable bond so that you can easily get them to and from their cage and are very familiar with their personalities and habits you could then move on to a larger glider proofed room.
Each glider has their own personality and will bond on their own time schedule. It may likely take months to get to what is a 'true bond'. They will become more comfortable with you before this and the biting may stop during this time but, the full trust takes awhile.