Yes, you can use other frameworks within Adobe such as JQuery. Using additional frameworks lets you extend the functionality of Adobe Experience Manager.For information, see Integrating the JQuery Framework into Adobe CQ.
Yes, you can create AEM applications that can consume a third-party web service. For information, see Creating Adobe CQ bundles that consume web services.
You also don't want to insert you resizing efforts prior to calling the image.draw method. The draw method doesn't actually render the image, it draws the HTML img tag that your components print out. If you were to use the ImageHelper to get the layer and resize it that would not actually change th...