sound proofing

One option would be something like Roxul AFB. It's a rock wool insulation batt that installs similar to fiberglass, but is designed for soundproofing more than thermal insulation. Up here in Canada you can get it at Home Depot among other places. I used it for part of my utility room walls and it seems to work well. Costs more than fiberglass though.

As for the ducts, you can frame around them for sound dampening insulation.

Chris

Like this?............

Forced air and soundproofing are very nearly mutually exclusive. And starting to figure out what you're doing "a few days" before you have to be finished guarantees either a bad job, or a missed deadline.

If you're trying to reduce sound FROM the air ducts, make them bigger. If you're trying to reduce sound THROUGH the ducts from one room to another, make them smaller, and do independant runs and returns to the furnace for each section.

In all cases add as much weight to assorted sound-transfer surfaces as you can. Decouple the surfaces where sound is generated from surfaces where you don't want sound tranmitted.