It's really big just take a look at my vield up in the right corner taking a sunbath! how big does the cage need to be for a vield, what measurement. because i've seen vields in much smaller cages.
yeah thats ok for size but i would get rid of the substrate they can accidentally ingest some while shooting at food or mistake it for food that can lead too impaction and that can lead to death
my floors are all bare if your misting you can make a drainage for the cage and if your using a dripper just put something under it to catch it for you to empty later not as attractive but better than the alternative of impaction
if you really like the terrarrium look you can get a reptibreeze for your vield and use that tank for smaller pygmy chameleons, they live on the forrest floor and will thrive in a terrarrium
I use Cage Carpet for my cage its fairly cheap and easy to clean i just take it out every few days throw it in the shower to clean it out and wash the poop off...works good for me although it does sometimes get to much water and then i just take a dry washcloth to clean out the bottom of the cage before putting the carpet back in
yeah you can use the carpet if you want but it is a lot of maintenance you have to keep it clean and sanitized all the time or else its a breeding ground for bacteria