[cypher]

Great to hear you've given this little one a good home

I think saucers should only be used as an extra wheel & the main wheel in the cage should be an upright wheel, which wheel you can get will depend where you are but as long as it spins freely anything up to 8" is fine.
I use water bowls rather than bottles for all my hams & as long as you have a little shelf or the top of the house, any stable surface a little above the substrate that would probably be a better option in a tank.
If the paper he was on was shredded rather than just torn up I would be worried about sharp edges as well as ink, again which substrate you could use will depend on which country you are in but a good one available in both the UK & US is Kaytee clean & cosy, white only.

For chews you can try hazel or apple wood sticks but the most popular chew with all hams is a whimzee dog chew, the little toothbrush would probably be best for a robo.