We live in the San Francisco Bay Area (San Jose) and need to insulate our attic and walls. We have two bids. One for cellulose and one for Fiberglass. Both blown. I would prefer to business with the bidder on the cellulose but I am not sure which material is best.

What are the pro's and con's of each. Cost is similar.

Should the old blown in material from the 60's be removed first in the attic?