This series is pretty basic for someone who's already a programmer, but it will give you a good introduction to app developing. This is a more advanced course, which gives you a better introduction to the whole idea of the UWP in the first few lessons and presents a few examples that have helped me a lot.
What tools will you need? Visual Studio Community is ideal for developing Windows Apps -- it has a great code editor, a good debugger, and nice visual design tools (check out Blend for Visual Studio) and previews.