Hi Christian,
I haven’t read it myself, but I’d imagine The Legal Guide to Costa Rica is a good overall reference. I don’t know that it would have more information about residence than that which is provided on the web page I list. That really does break down all the steps to applying for residence. That is the checklist I followed myself when I applied.
You can also find a document checklist and some of the forms you need to fill out with your application here: http://www.migracion.go.cr/extranjeros/residencias.html
As far as applying for residency, I do recommend hiring an attorney to help you with the process, unless you speak good Spanish. It’s usually much smoother.
Jason