Ok, the crawlspace under our house got flooded. One company said we
needed to have the insulation replaced on the duct work under the
house as well as have the plastic removed that covers the ground and
get fungicide put down. They want to charge about $8400 to do this
(about half just to do the ground/plastic). Another company said we
needed to actually replace the ducts which would be about $7000 but he
doesn't insulate them which doesn't make sense to me. We haven't
smelled any musty odor or anything coming from the air vents. Anyway,
my questions a

1. I assume that HVAC contractors are the people I need to get
estimates on for this work correct?
2. What exactly goes wrong with metal duct work when it gets wet that
you would have to replace them? Do they rust or something?
3. Do these prices sound reasonable (I intend to get more quotes)?
4. What additional work if any would you need to have done with
getting your crawlspace flooded?

Any additional thoughts/opinions are appreciated also.

Thanks