For cleaning, what I personally do is that I us vinegar/orange cleaner I make myself. Here is how:
1. Get a large jar.
2. Fill it with orange peals.
3. Pour apple cider vinegar (I think white vinegar works as well, but I haven't tried it) to the top.
4. Put lid on and let it set for 10 days.
5. Pour it all on a spray bottle and fill the rest with water.
Once a weeks I clean toys, wheels and cage with this, scrubbing down really well and letting it sit for 5-10min, then rinsing everything and drying the cage with a towel, and if at all possible letting it sit in the sun until it is completely dried. If I am out of this cleaner I use soap instead, just make sure is really well rinsed.
Diets is something you must choose for yourself and your gliders. It does not matter if it is an excellent diet if your gliders won't eat it. Here are links to diets:
www.sugarglider.com/gliderpedia/index.asp?Diet
Your gliders are probably going to be weaned to a specific diets, so try ask your breeder what he/she feeds them, they are more likely to eat this once you bring them home with you. If you are not sure if that is a good diet it, feel free to ask in the forum, someone surely will answer you.
The last question I think is about bedding. It is your choice whether or not you choose to use bedding. As long as you clean the bottom pan often, it should not matter what you choose to do. If you use bedding, just try not to fill it all the way to the top, so your gliders won't reach their own poop, and rotten food they threw around. And stay clear of pine or cedar shavings. I haven't used fleece lined waterproof crib mat, so I can't give you any feedback on this.
Hope this is helpful!