Does the underside glide smoothly on clothing allowing for easy positioning or does it hang and pull on your shirt/jacket?

Hello, With the back of the M26PD-DBR_DBR being Garment leather, you'll find that it smoothly moves on your clothing. The Leather that generally grabs at your clothes is going to be Suede leather, which is meant to be grippy. If you have any other questions, please reach out to us directly. Thanks!

Does this fit a dreadnought?

It probably can length-wise, you may want to measure the likely length on your guitar with a string or cord and confirm. You’d need to provide the attachment clips and hardware on the guitar. Not all acoustic guitars come with these things.