You can't pull active lease info.
You can't pull vlan info if vlans are not enabled. It's simple to check if vlans are enabled, and simple to enable them. Even if you only have a single vlan, imho, the benefit of manipulating vlan info via API is greater than the risk.
You can pull per-vlan per MX network if a dhcp server is active, scope, reservations, exclusions, lease time... Go here for complete list.
I've been using this heavily to build a report of management IP assignments on Meraki equipment per organization, specifically if they're static or DHCP, and if an MX on the same network has a lease. 600+ lines of code later...