Some drums come with a felt muffler, most companies use it as an option. Factory will have it incorperated in the drum.
If you`re going to make your own, the with is to taste but leave it a little long to come out the hoops. People do that to tighten it back up when it stretches. pull tighter to change tone.
I never suggest the pillow unless you remove it after gigs or practice ect. A pillow in there all the time will leave a moisture stain on the wood but the SS kit don`t need to worry bout that !!