No problem, we all have to start somewhere.
You can run both serial and idn printers from the same workstation. The Network Node setup has a tab for Com Ports. You probably have port 4 set up already, and you can add port 5, (which I think is the serial port), by clicking the blue plus side above the Baud Rate dropdown box. I haven't configured a micros serial printer in probably at least 12 years so maybe somebody here will help with that.
Is the lab system you have using the serial as a check printer and the idn as the order printer? That's a common setup, and will determine how you treat the printers. Check printers have to be set up in the Devices screen, but not in Order Devices.
The top part of the print class determines whether the items linked to it print on guest checks and reporting. Most items will print to everything but the Local Order Receipt and Fiscal Cash Register. Common exceptions are items and messages that are instructions for the kitchen/bar, ex. meat temps, no salt, extra ice, etc... These are usually just sent to the journal printer in the top area.
Fiscal Cash Register - I think this is an external device that can be connected for auditing. Never used it personally.
Local Order Printer - this makes the item print on an order chit at the check printer for the workstation. I use this for guacamole orders. Our Mexican restaurants have table-side guacamole stations, so they can't have a printer. Guacamole chits print a the workstation, (Local Order), when a server places an order, and the server then hands it off to the guac station.
You're definitely confusing yourself with physical & logical printers, and probably jumping back and forth between screens. Order devices have nothing to do with express thermal, autocut, etc... those are Device setting. It sounds like you may be hitting the little yellow folder icon
As far as printers go, think of the Devices setup as physical equipment that you can touch. This is where you tell Micros what kind of hardware you're working with.
Order Devices are logical devices. Try not to think of them as printers, but as the prep station they're used for. They're usually linked to a piece of hardware with the same, which causes some confusion, but that's not necessary. You can have multiple order devices linked to a single physical device.
[ol 1]
Just try not to get frustrated, go through the tabs one by one, and try not to jump back and forth at first.
[li]Network Node - define anything with an operation system[/li]
[li]Devices - link workstations and kds units to network nodes and define your printers[/li]
[li]User workstation - tell the system how your workstations should behave[/li]
[li]Order Devices - define the stations that will be receiving orders and link those stations to a physical printer/kds.
One thing we didn't mention is redirection. Once you have the Device saved for your Order Devices, set the Redirection Device for each Order Device to itself. (Hot goes to Hot, App goes to App, etc...).[/li]
[li]Print Classes - set up the routing you need to get menu items to the correct prep stations.[/li]
[li]User workstation - go back and tell the system which order devices each workstation is allowed to use[/li]
[/ol]
You may want to use different names for things in your lab. Like calling a device D-Hot and the order device OD-Hot. It just makes it easier to tell if you're selecting a physical or logical device when you're on other screens. So in the Order Device setup you'll see selections starting with D- in the Device and Backup Device dropdowns, but OD- in the Redirection Device and in the Print Class setup. I did this year ago when I was trying to figure out how condiments worked and it really helped. Speaking of which, I'd suggest you get regular menu items working before worrying about modifiers. They're going to bring Menu Item Classes into the mix.