Dave,

Two things.

First, you will find that you can get perfect color if you invest in a system, either card or plastic cube, that has White/Black/Grey patches that you can use to set perfect White balance after-the-fact. Q-Card is an inexpensive printed card system. But, my favorite is the SpyderCube from DataColor. It is a plastic cube having white, absolute black and grey features. It's works magically to allow you to use PhotoShop to pop the colors into place with three simple dropper clicks.

Secondly, shoot in RAW rather than JPG. That is probably not possible with your current camera. RAW give you a LOT more control over the colors when processing your images. Most all of the dSLR cameras provide you with the ability to shoot in RAW. The Canon series goes one better by giving you a free tool to process the RAW images with a few simple clicks. If you do want to try an SLR, then I'd suggest the new T4i as a wonderful choice. I no longer use Photoshop for processing my images because Digital Photo Professional that comes with Canon cameras is so easy and good.

As for depth of field issues, take a look at photo stacking applications like Helicon focus. ALL cameras have limited field of view and products like Helicon Focus can be used to over come those limitations.