LTG,
1 - Flash/Silverlight is not a must components. but if the browsers installed it, the uploader would provide better functions.
2 - AjaxUploader are compatible with/without Ajax , please check our online samples, the samples can switch Ajax mode.
3 - You can use any javascript library , but need understand how AjaxUploader works and make sure the JS code can works with the Uploader.
Regards,
Terry