Correx is most commonly used as a base for c&c (indoor) cages but it works so well for protecting the wood for outdoor hutches!
Yes its an alternative to shavings.
Megazorb is a bi-product of the paper making industry. I really like it, one of the most absorbent beddings Ive come across (I prefer it to shavings). I do a full clean once a week but wet bits of megazorb get removed daily.
I found when I did originally use hayracks that mine actually ate less hay than they do now I dont use racks at all. They love being amongst big piles of loose hay. I get my hay from Haybox. I use meadow hay primarily for bedding and the soft cut Timothy hay for eating - again, just a couple of loose piles of the soft cut into various areas of the cage. Their hay is topped up a few times a day. Wet hay is removed daily and replaced.
You can only gauge their hay intake by their weekly weight checks, not by eye - so it may appear that they aren't eating much, but if their weight is going up and you are feeding only the recommended and limited amounts of veg and pellets, then their weight gain is coming from hay intake as it should be. They will not eat all the hay you put in, which is why topping it up regularly keeps them interested - they like to forage through and pick out the best bits!