Yes they light up, yes the bulbs all break, and yes they can be replaced - but it's fiddly. http://www.renaultforums.co.uk/17-electronics/122222-window-switch-bulb-replacement-lag-ii.html I used these - https://www.rapidonline.com/truopto-osw5dk3131a-12v-12v-3mm-white-led-4200mcd-55-0897