-You can take the link I posted to educate yourself on how to build such an extension or hire a 3rd party to do such development for you. IQNOX is one example of a PTC partner with skill in that area.
-Vuforia Studio is not related to what you requested, unless you want to use mobile displays or 3d glasses to consume data in AR.
-The extension SDK will not be needed as it is mainly for developing extensions based on java code. A widget like you described will need extension packaging but will be executed on client side (in the browser) using SJ and not on server side.
-Which JS libraries will be supported by TWX in the future is a question to direct to PTC support and product management.
Also note there is already an D3 based bar chart widget available in the custom charts extensions you can use as template for your own extension. https://support.ptc.com/help/thingworx/platform/r9.7/en/index.html#page/ThingWorx/Help/Extensibility/BarChartWidgetExtension.html#