Try the "find local pros" feature on this site. As to whom you "need" to hire, this gets to personal preference.

An Architect can certainly help you with this, and would be fully qualified to tackle pretty much anything you chose to do down there. An Architect may be overkill, but on the other hand will assure that you have all your bases covered. Most US municipalities outside NY won't require an Architect for something like this, you should confirm that locally, but that doesn't mean you can't use one.

An Interior Designer is generally qualified to do the layout portion, but not by default to deal with (or even recognize) the variety of building science issues you may face, especially regarding moisture / thermal / condensation issues, and some code construction issues having to do with framing against concrete.

An un-licensed designer can also help with layout but would be generally again a step less qualified than the ID, notably with respect to general code issues regarding layout and interior environments.

In all cases, if a permit is required locally, you should go that route. It assures at least one layer of a qualified local professional assuring what you are doing down there is safe and healthy.

Good luck! :-D

Thanks- I'd really like appreciate your response. I would like someone who knows the code issues where we live as well a some guidance on moisture issues b/c it seems like there are many different approaches to moisture control.

ReSquare is correct.