Need help - CV boot torn - how to keep the mechanic honest

[Werewolf]

Hi all,

I need some help. Today I noticed my front left outer CV boot tore. Why? B/c I noticed a clicking sound at low speeds from the front right wheel area.

I've dropped off the car to a well regarded indy mechanic but I want to make sure I don't get screwed in the repair process.

How do I know whether or not the CV joint is damaged?
If it is damaged, what are my options in the repair process at this point?
Do I need the entire axel or not?

What are reasonable costs for this kind of work? Sorry for the ignorance but I just don't understand suspension work / parts. The shop charges a $100/hr for labor which is steep but ok.

Thanks for your help!