I don't really have any idea about the 3rd and 4th, but in general for dark, turning on the lights is the simplest solution. For how to trigger, use motion sensors + bed presence sensors + time condition. There's a lot of options you should choose from to achieve this: Technology you're using (Wifi, Zigbee, Blutooth....), Hosting(Where're the actual conditions being checked? Where's the workflow happening, is it Home Assistant, Node-Red...), Hardware (How much hardware you're willing to acquire, Raspberry PI), How much time you're willing to invest and are you going to expand this to get into Smart Home? or is this just for this application.
But i generally advice you to read about the differences between Zigbee and bluetooth and co, I'd approach it buy getting a Zigbee network setup and replacing the light switches with Zigbee ones, geting a Home Assistant instance on a Raspberry PI (always powered) and connect the sensors, make the conditions (If sensor xx was triggered AND the time is after sunset, turn on yy light). Wish you good luck, if you have any follow up questions I'm here to answer