>Assign all devices with a static IP?
Apart from L3 gateways, I never use static IP addresses for Meraki device management. Switches, APs, cameras, everything.
Pure dynamic. No reservations.
I do use reservations for things like printers.
>Use Google DNS for each device?
Sometimes I use internal DNS, sometimes I use public DNS. I often use 8.8.8.8 and 1.1.1.1, as I have had customers whose ISP lost connectivity to Google DNS, and it is a bit catastrophic, so I like using two different DNS providers.