Great Site Tax Guru's!!

Okay I really don't know where to begin. I'm in the process of starting a new retail business in Washington.

I'm trying to decide whether or not it would be a good idea to use my previous LLC that I filed back in 2005 in which I never conducted any business since or completely file a new entity to start up this new business.

My question is, Would it be a disadvantage to use a LLC that was filed back in 2005 vs. something that is filed more recent?

At first I was actually thinking of registering a new trade name under the current LLC but I wasn't sure if that was permitted.

Another question that I have is:
Pior to staring this new business of mine's. My plan back in 2005 was to have an LLC filed so when I was ready to do business it would save me some time.

At first, my goal was to have a few different businesses under the same LLC. Then I started to wonder if that was even possible. I wasn't sure how I would file the taxes if all the trade names shared the same UBI number.

For instance, I have an LLC formed as "Endless Investments, LLC" Now I want to open a retail dollar store at one location and open grocery store at another location using different trade name but under the same LLC. Would that even be possible?

Thanks,
Rick