Some of this is spot on, but I'd still say that you can get 95% of the way there by doing relative mixing, rather than focusing on having the right gear.
What I mean by this is you can create a great mix simply by A/B-ing your track with another one that you really like. By doing this type of relative-mix, you are removing the speaker from the equation (mostly). Having said this, I'd still recommend having a decent pair of speakers or cans to listen with, but instead of focusing on the gear, relative mixing can do amazing things. Also, listen to a lot of music on your monitoring setup of choice, to get calibrated to the setup.
WRT the Mono/Stereo debate: I use the stereo field extensively when mixing, by placing various elements in their own place...I'm a big believer in stereo mixing. However, it is a good idea to check the final mix in mono, to make sure no low-end phasing issues arise. Your bass and kick (and low parts of the snare) should be panned dead nuts center 99% of the time, which should help to avoid this! But trust me, there are plenty of very, very popular producers today whose mixes sound like rubbish in mono, and they are well-aware of it.