Hi, at the top of this Habitat forum is a "useful stuff and frequently asked questions" Announcement that contains links to articles
such as this one on substrate and litter
you might want to read through all the options there.
I use Finacard shredded cardboard as a substrate as my rats enjoy spending time foraging for their food in there instead of just picking food out of a bowl. They also like selecting certain bits to carry to their beds. I buy it direct from the supplier, the same as their paper based pellets for their litter trays. I have not had a problem with dust.
You can also buy those products from RatRations
which has a great selection of different items for your rats.
I use them to buy my rats food (again, at the top of the Feeding forum is an announcement with articles on feeding
that are worth a good read through). I get the 11a mix
, however those mixes all need you to provide extra supplementation of Vitamin D, Calcium and Copper which can be done with a power you sprinkle on wet food (weetabix, yoghurt, couscous, veg) 3 times a week, or a supplement in their water.
Not sure how large your cage is but consider getting three rats, better cage dynamics that way and if one dies unexpectedly you won't be left with a lone rat immediately.
Hope that info helps, happy to answer any more questions