Question in the title
I Was running an integrated Tail light (This one: http://www.ebay.com/itm/270767591392) until I got a friendly warning from a copper telling me they were illegal in Australia - It was promptly swapped out back to stock. Installation was fairly simple, remove old light - wire up new tail light and install. As for Flush mount signals, are you meaning ones like this:
(http://i.imgur.com/S4ZawnM.jpg)