1995 325is E36 Window arm off track

When it was really cold out a few months ago I tried to roll the window
down. It was frozen shut and the motor in the door ripped the moving
arm from the track attached to the window. So I took apart the door
and reconnected the motorized arm to the track (presumably saving
myself $200). But the connection didn't stay. After about 2 weeks of
using the window the motorized arm and the sliding track it attaches to
came apart again. I am assuming they came apart because I couldn't get
the cotter pin in to hold it all together.

So I have 2 questions.

1. How do I disconnect the speaker wire from the speaker? It seems
like its a simple snap-in but I can not figure it out for the life of
me.

2. How do I get that damn little cotter pin in position to hold the
motorized arm attached to the sliding track?

Any help in this matter will be greatly appreciated. Thanks.