Hey, Nima
Please see my responses to your Questions below:
1. Can multiple people train the same agent simultaneously or will this cause problems?
RESP:
This is not advised as it can cause conflicts. This is indicated in the Dialogflow ES documentation[0] as a note:
"Developers should avoid working on the same agent at the same time. This can cause conflicts when saving and training the agent."
2. Can one person have multiple tabs open for the same agent and be working across all (eg. Training, Intents, and Entities tab) or will that cause problems?
RESP:
The same comment in Question 1 above applies.
3. I have always worked in the Essentials Edition, as opposed to CX. What are the advantages and example use cases for each edition? Is one preferred for a certain type of bot?
RESP:
As highlighted in the documentation[1], The Dialogflow Essentials (ES) Edition provides the standard ES agent type while the Dialogflow Customer Experience (CX) Edition provides the advanced CX agent type. The article[2] highlights the comparisons between the ES agent and CX agent.
I will like to point you also to this[3] comparison of features between the Dialogflow Essentials (ES) Edition and the Dialogflow Customer Experience (CX) Edition. Some of these comparisons highlight use cases where each of these Editions are suitable.
[0]
https://cloud.google.com/dialogflow/es/docs/access-control[1]
https://cloud.google.com/dialogflow/docs/editions#cmp[2]
https://cloud.google.com/dialogflow/docs/editions#agent-types[3]
https://cloud.google.com/dialogflow#:~:text=all%20technical%20guides-,compare%20features,-Editions