For your question 2 (How do I detect silk browser user agent in jquery)
Basic Silk identification
if (/\bSilk\b/.test(navigator.userAgent)) {
alert("Silk detected!");
}
To detect mobile/desktop preference
var match = /\bSilk\/(.*\bMobile Safari\b)?/.exec(navigator.userAgent);
if (match) {
alert("Detected Silk in mode "+(match[1] ? "Mobile" : "Default (desktop)"));
}