1) One LLC = one EIN

2) One LLC = one license/permit

3) It's your choice. You could have one bank account for each dba, or one account to accept payments for all dbas. You just want to make sure your bank has your dba on file and adds it to your account so you won't have any trouble depositing a check that a customer makes payable to your dba name instead of your LLC's legal name.

4) Depends on whether UPS will let you accept mail addressed to the different names at one box. But as far as filing the dbas go, there's no requirement to have a different address for each dba. One person with one address could conceivably have 100 diffferent dbas.

A dba is just a trade name, a name other than the LLC's legal name under which it will do business. The LLC still remains one entity.

Your businesses might have a relatively low risk at this point, but no one ever can be assured that they won't be sued. Esp. nowadays--according to many asset protection firms, the average American will be sued 5 times in their lifetime. Not saying that you absolutely should form multiple LLCs, but just a recommendation that you carefully consider this before lumping two retail businesses and a service business (and, by extension, all of their revenue and assets) into one LLC.

Having said that, filing taxes for a single-member LLC would involve completing one Schedule C that gets attached to your 1040 tax return. But it probably wouldn't be that much more difficult to have 3 LLCs with 3 Schedule Cs. Might take a little more time but, if anything, you'd have a clearer picture of how each business was doing. At the end of the day, though, all of the income (whether 1 LLC or 3) would pass through to you anyway. So no difference, tax wise.