My initial thoughts on this is to reserve the IP address for each printer so that the IP address is now "synced up" with the MAC address for each printer. This will ensure a static IP address for each printer.
Yes. Some companies have limited resources based on the equipment. Since most equipment is idle for a large amount of time (printers are not printing constantly), the IP addresses are released to other devices to use. So conflicts may ensue because of this time division multiplexing by dropping dormant devices.