Welcome to United Bimmer! I have posted the Bentley Service Manual and Haynes Manual Dow load links in the E36 section. Please feel free to download scoot for your reference. Our Knowledge Base has an excellent section of DIY writeups with more on the way. Feel free to have a read through them and see if they help.
As for the bulbs in your taillights: Their is a plastic cover on the back of the taillight inside the trunk. The cover has a small dial in the center of it you rotate and the cover pulls off. Each bulb sits in a lamp socket inside the taillight housing. The lamp sockets rotate and pull out. This gives you acess to the bulbs. The bulb turns and can be pulled out. Check to make due the bulb sits securely in the lamp socket and doesn't have any movement. The lamp sorts wear out over time and can need replacement. I've replaced two in my car.
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