Can I login with 1 operator's ID from multiple devices?

Yes, you can.
With ChatPlus, you can login with 1 operator's ID from multiple devices, so it can be operated in many ways.

Login from company's PC and smartphone app

When you are working, you can chat from company's PC and when you are out of the office, you can login from your smartphone and chat from it.
When you are eating, or cannot be at office, it is very useful to login from smartphone app. (If you install the app, you can get notifications when a chat starts.)

Create common ID and share chat within team members

Set ID for a common agent such as [Support window] and ask multiple members to login at the same time. If an inquiry comes, a member having free time can reply back to the chat.

For homepage with under 200 inquiries, you can handle them with only 1 ID.
For example,

A usually replies back to chat
If a question that cannot be answered right away appears, create an alert
When an alert is created, other person can reply back
Other person would reply back depending on questions

Like this, you can set the operation rules beforehand, to stably operate chats.