How important is amalgam removal procedure?

I posted a question to Shelley about this problem
and wanted to get feedback from this forum as well.

I have a fractured molar and it has a large amalgam
filling. The dentist wants to remove it, replace the
filling and crown the tooth.

* How important is the "dam" and alternative air source?

When I questioned her about her protocol she says
they use water and high pressure suction. IS this
enough?

* Is the mercury leaking out because of the fracture?

* Should I just have the tooth pulled?

* Do crowns typically cause problems?