steering column questions

[shrike]

So, I'm in the middle of replacing my turn signal switch and I have a few questions.

Disclaimer: I know almost nothing about steering columns, so please excuse any ignorant questions.

1. I have the switch out, and the aluminum piece underneath it is just sitting in there loose.
Is that correct?
It looks as though the only thing holding it on is the 3 screws that hold the turn signal switch on.

2. The bearing in the middle of that aluminum piece has seen better days. Are replacements available?

3. The threads on the end of the splined shaft that the steering wheel is bolted to are kinda chewed up. Is it possible to replace that shaft short of taking out the whole steering column?

Thanks in advance for any advice!
Scott