Look for any hotel near the convention center (also listed as downtown/warehouse district) and you'll be within easy walking or short cab distance to the port. I would park at the hotel, not the terminal. You can check rates and ask for details about parking if you book thru NewOrleans.com and use their call center (full disclosure: I'm the editor of the web site...)
The port is very easy to find (it's next door to the Riverwalk mall/behind the convention center), but leave time for heavy traffic, etc. -- I was on the Voyager trip last week and the terminal was chaotic and traffic was a nightmare. They're working hard to fix the glitches from that first big excursion out of the port, but be prepared.