First problems solution, get new clips...cost you all of $4 from BMW...lol
Second, get a new trunk gasket, also cheap from BMW
and last...replace all your bulbs with proper silver based bulbs...all new ones...should eliminate the dimming and intermittent tail light notification...no joke...
Pleaaaaaase don't use glue and tape...it's not the answer. Don't be afraid to replace things

its a BMW, not a Honda...tape isn't the only option...lol
Parts are cheap...buy em