Here is a bunch of links to resources that will help you get up to speed on what's new for developing Windows 10 applications.
Want to download Visual Studio SKU's including VS 2015 click here
Everything you needed to know to write applications using MS Tools
Windows 10 and what's new
Get Started
Design
Develop
Publish
Want to take Microsoft Virtual Academy (MVA) Windows 10 Courses click here
Channel 9 has some great windows 10 related videos here