Some information - https://www.usmint.gov/news/press-r...s-w-mint-mark-circulating-quarter-collectible
I assume MWR means Mint Wrapped Roll. As far as I know the mint doesn't sell rolls of mixed dates so I guess you mean bank wrapped roll.
Yes, they come from one of the coins and currency services like Brinks, Loomis, etc. Mine was from a Loomis roll.
The only W people are referring to in terms of circulation are the W quarters paddyman98 linked above. We did get several 2019-W Cents minted this year, but you won't find those in pocket change. And if you do, go buy a lottery ticket and watch out for lightning.