I'm going to be honest - I don't think the tank is worth the money. I got the fluval chi and modified it for saltwater. Ended up taking out the filtration/light cause it wasn't suitable for saltwater. That left me with the cube. I could have gone to ikea or some other place and found a nice glass cube for much cheaper.
I added a mini canister filter for filtration. TOM'S makes one for cheap, but that one leaked, so I bought the 504 canister filter they sell at Petco for turtles. It's been working great. I hide the intake and outtake behind decorations.
I bought the finnex Epoch Cliplight (http://www.finnex.net/index.php?page=shop.product_details&flypage=flypage.tpl&product_id=176&category_id=4&option=com_virtuemart&Itemid=61&vmcchk=1&Itemid=61) and my macros have been going crazy for it! The light was cheap, looks nice and is the perfect amount of light for any coral, including sps (I have a tri-color valida that is doing amazing).
If you want an all-in-one, I recommed the fluval spec. I just purchased it for work and love it! It's got the hidden back compartment that gives many options for filtration. I did substitute a coralife mini aqualight for the led.
I prefer snails to crabs. Hermit crabs are little devils. I think the size is too small for 4-5 fire shrimp. I'm going to get 3-5 sexy shrimp for my fluval spec. I would recommend you stick with smaller shrimp.
I recommend deciding first what you want to keep - researching the requirements for that coral/invertebrate/fish - then choose a tank you like that meets those requirements.
Another consideration for nanos - water evaporates quickly out of an open top tank. I have to top off my tanks daily using a pitcher.
Feel free to pm me any other questions. I've done all different size nanos - 2 gallon, 2.5 gallon, 5 gallon, 12 gallon, 24 gallon and 29 gallons. I'm happy to share my own trials and errors with you.