If you do decide to insulate have a look at Roxoul insulation. It is easy to install, is fire proof up to 2150 fahrenheit,has excellent sound deadening, does not promote mildew or fungi,does not contain any fiber glass and it is chemically inert( CFC and HCFC free)
I purchased a Buck BD4801 4X36 belt sander with an 8" disc for my wood working projects and am happy with the way it works. I have not had any problems with belt tracking in the the year that I have had it.
I have tried serveral different brands of of Sound deading mat. The one that I have used the most is Canopus on Amazon at 18 SF for $29.74. As a bonus it is made the the U.S.A.
I have a Holeshooter that I purchased in the early 80's and it is still running stong. The only thing I have done to it is replace the power cord. If I needed to buy a corded drill today I would buy a Holeshooter in a heart beat.
I have been using a product calle Free All for awhile now and like it better than anything that I have tried in the past. It is around $10 a can but it works well in my opinion.