Welcome to HC & congrats on getting Nogi
It sounds as though your cage is probably a little small, levels aren't important & depending on how high the cage is can be a potential fall risk especially with Russian hams.
They really need more space on one level, a lower ledge or shelf is ok but doesn't actually count toward the cage space.
I find 80x50cm to be a good size for most dwarf hamsters.
The main thing is to have lots of deep substrate (at least 15cm, more if possible) in the base, a house that's large enough, with no base placed directly on the substrate so your ham can dig & burrow down a bit to make a nest.
The hides, toys, chews & sand bath all sound good, hams aren't often interested in a lot of things sold as chew toys but you can't really go wrong with whimzee dog chews & some will enjoy willow and apple sticks to chew on.
You really don't need to clean the cage weekly, it can be very stressful for your ham to over clean the cage as they need to have their scent all around them.
Just spot clean any pee, if your ham uses a litter tray or the sand bath then that makes life very easy.
If the nest isn't peed in at all then leave it alone as much as possible, check it now & then, maybe every few weeks & if it's getting a bit smelly you can just replace some but never all of the nest material.
If the food hoard has fresh food like veg in it you can remove that but otherwise it's best to leave that too as they will eat from the hoard, if it does begin to get really old then you an just remove it & put some fresh hamster mix back where it was.
The rest of the cage won't need cleaning often & I would never do all of it at once, maybe clean about a third or half at most once a month if needed, don't just clean because you feel you should, hams are very clean & unless something really needs cleaning it's best left alone.
Just in case you don't already know Campbells & Russian hybrids (if your ham came from a pet shop he is most likely a Russian hybrid) can be prone to diabetes so you do need to take care with his diet, no sugary treats, nothing with honey or any kind of sugar, fruit should only be a very rare treat but the less sweet veg are fine to be given daily once you ham gets used to them.