I don’t have any Hues so I cant give you a definitive answer… but I think you cant change the default startup light/color. You can immediately change it to a different one right after they are turned on though using the WeCore SmartApp. https://wiki.webcore.co/ . There is a little bit of a learning curve to set this up but it is well worth it and documentation is great. You can use this forum thread for specific questions for your setup:
The easiest way to achieve (2) is to use the “Speaker Companion” app. You can find it in the phone app → Marketplace → SmartApps → Music & Sounds. Or you can just use the WebCore app I mentioned above.