For this post. Yes, the plastic cover is removed prior to installation. As far as getting the ball into the steering knuckle, just make sure the ball is lined up in the same vertical plane as the knuckle and it should just slide in. I did mine a couple of months ago, and used the floor jack to put a bit of pressure under the c-arm just to the inside of the ball joint area, and it slid in like butter. You'll want to eye it as it slides in so that it does not go in past the rastener groove on the ball.

the last post. sounds like what happened is, there was some spring energy and when the ball dropped, the spring caused the entire unit to move forward. Inspect the lines, and associated mounting brackets. If the ABS wire got damaged, you should see the ABS light illuminated in the cabin. Now, mind you, this is only speculation on my part as, I did not have the same thing happen to mine.

Also, you will need an alignment regardless.