Choosing whether or not to use a travel agent is more about your personality than price in my opinion. If you get a travel agent you should use one that specializes in Disney. A good travel agent will check every new discount that comes between the time that you book and March and will rebook you each time a better deal comes out. There's no fee to you, so this is a great way to go. The downside is, if you want to make a change to the reservation you HAVE to go thru the agent, Disney won't talk to you directly. If you're more of a control freak type and actually enjoy doing the research use Mousesavers.com to keep track of current discounts. The end result should be the same price.
For dining, check out Allears.net. They have all the restaurant menus, so you can peruse the counter service menus from home and make note of which ones have non-nugget type options. A couple that come to mind are Wolfgang Puck Express and Earl of Sandwich in downtown Disney, Cosmic Ray's in MK, flame tree bbq in AK, there are lots of others too.
Touringplans.com has a calendar that shows the least crowded park(s) for each day and also has some suggested itineraries. You have to pay a subscription fee to see March dates now, but if you wait until closer to your trip you can see that information for free.
Read everything you can about Fastpasses, it will make your trip so much more enjoyable to use them as much as possible.
The disboards has a great search engine. I have the most success with "show posts" versus "show threads." If you can think of a question, it's probably already been asked and answered!
Have a wonderful trip!