I will say that if someone is just starting out in publishing, then committing to only publish on Kindle is fine, but they only give you 5 free days out of 90 to promote your book.
If you pay to advertise during those 5 days your sales will sky-rocket.
I find it extremely satisfying to see my name right next to Martin's for something like a New York minute.
Once the free days of promotion are over, you will be smothered under 400,000 titles until you're so flat that you just evaporate into thin air and are never seen or heard of again for a 3 month period which can feel like an eternity. .....I'm mean like forever, forever.
The info on the blog page isn't that out of date, but it's a bit minimalist. I'd recommend something a bit more detailed. For *all* the details, I recommend David Gaughran's book Let's Get Digital, and when you've got the thing published (to avoid being smothered under 400,000 titles, as MineOwnKing describes it!), I recommend the companion book, Let's Get Visible, which covers the marketing side of things. Personally, I don't find the free days to be quite as useful as discounts - reduce the price to (say) $0.99 and then promote.
For the most up-to-date information on self-publishing, hop over to the Writer's Cafe on Kboards where people who've been through the process are very friendly and helpful to newcomers.