Do all marketbaskets in mass have the same sales in their flyer every week

I would guess it's each store. I'd be surprised if it wasn't.

I don't know about that, but I do know they all don't have hot lunch like the one in Hudson, MA.

All stores with ad listed on back. Front page sometimes starts saturday but mostly starts Sunday.

No idea. But if you look around on the flier (typically on the back or iside back page) they will include an address of the participating Market Baskets. If it does not, then it is for all stores.