EVE was pretty poor for multiboxing as it required mouse input for virtually everything. Recently they've introduced a wider range of keyboard shortcuts (only took them 7 years...).

I'm using ISBoxer for account/window management and key broadcasting. Lax is currently working on improving the mouse broadcasting features for EVE. I don't know much about the other software options as the only other one I've used is Keyclone but that didn't work with EVE last time I tried it a couple of years ago.

For dualboxing my best piece of advice would be to make sure that both pilots have the same skills and ship. Flavour of the year is the Drake battlecruiser for simplicity and firepower.