[Can you remove the USB during printing?]

We are only able to print via a USB at the moment. I'm wondering if the USB stick with the print file needs to be attached to the machine for the full duration of the print or if it can be removed once the print starts.

[Extra Column During Dual Print]

Thanks @SandervG,

So if I were to turn that option off the side effects might be some unwanted residue from the opposing print core or material from the functioning core may not extrude immediately?

[Extra Column During Dual Print]

When I print PLA with PVA support material (and maybe other combinations, that is just all the materials we have) this extra column gets printed as well. I assume it is some kind of transfer/cleaning process between material layers? I couldn't find reference to it anywhere.

[Monitoring Available Material During Printing]

My office has just purchased an Ultimaker 3 Extended. I'm wondering about the management of available material during printing. Does the machine do any type of tracking for how much material is needed during a print? Or is it up to you to check before you start? I'm aware the CURA program estimates how much you will need, but I'm wondering if the printer itself does anything with this information.

Related, if you were to run out of material during a print, what would happen? Would the machine continue the printer head movements, just with no material coming out, or would the print stop/pause in the middle? Since you are able to pause the print manually, if you notice you're running low on material can you pause and add a new spool mid-print?