All this stuff is very personal. Different people have very different tastes, and really you have to figure out what you think is best. So, my advice would be...
Get the monitors... IMO the Dynaudio's would be the best choice. Tannoy's probably second.
When you're getting good mixes done, get a microphone. This is way too personal a thing to give advice on, but its hard to go wrong with a Neumann.
When you've got that working well on your Digi003, think about upgrading the preamp, but don't do it until YOU can hear the difference. There's not really a whole lot in the preamp thing, so leave it until you really know what's what.