Hi I'm not an expert on taxes by any means, but I would recommend checking with your state regarding how many DBAs you can have under one entity because the small business regulations will vary from state to state. Try your Secretary of State's website or call them if you can't find the answer there.
The EIN is your federal tax ID number and assuming that your state allows for multiple DBAs you would need a separate EIN for each of the DBAs.
I hope that helps point you in the right direction! Hopefully someone who runs a similar business structure will chime in here as well