The first thing that came to my mind while reading your question was to use firewall rules, until I got to the point where you mentioned several dumb switches.
Since you said that you're new to network administration, I'll explain the mechanics behind some of this stuff and a (hopefully) easy solution for you.
Firewalls have ACL's (access control lists) which basically just control what IP addresses can go where. Your router/switch combo from your ISP has a firewall built into it. There's no way for me to know but I would venture a guess that it is advanced enough to let you create firewall rules. You can use these rules to allow or deny traffic from sources to destinations. If you didn't have any extra switches, then that'd be it and we'd be done... but switches are a different beast.
Network traffic in a dumb switch will not go through the firewall if the traffic is destined for another device connected to the same switch. Switches use something called a MAC address table. A MAC address is a unique hexadecimal number assigned to all networking hardware. A switch records which MAC addresses are communicating through which port. When network traffic comes in, the switch looks at the destined MAC address to see which port it should be sent through. If the destination MAC is connected to a switch port on the same switch then it just gets routed directly to that device thus skipping the firewall/router completely.
Using your existing hardware you may be able to do the following:
- Plug the cameras all into the same switch.
- Plug that switch into the modem/router/firewall
- Make sure that any devices you want to restrict from the cameras are
not plugged in to the same switch as the cameras.
This would make all traffic not from that switch route through the firewall and be caught by any firewall rules.
As for your printer security. This is probably best managed by whatever mechanism you're using to share the printer. I would share the printer with only the specific users who need access rather than 'everyone'.