You can download the Tizen SDK directly from the official web site: https://developer.tizen.org/sdk
Please check the System Requirements and Prerequisites in order to verify if your system is compatible to run this software development kit.
As for Tizen SDK 1.0 Larkspur, it currently runs on Windows*, as well as Ubuntu*. Tizen Web applications may be developed without relying on an official Tizen IDE, as long as the application complies with Tizen packaging rules.
The following docs & guides will help you out while setting up the development environment on your machine:
Regarding the second question about how to integrate applications with native components written in JavaScript language, I highly encourage you to participate in the IRC for Tizen: https://www.tizen.org/community/irc.
Regards,
Marvin O.
Technical Support Team
Intel AppUp® Developer Program
Intel AppUp® center
*Other names and brands may be claimed as the property of others.