What’s the etiquette for a wake/funeral of my sisters MIL

My sisters mother in law passed away a few days ago. I only met her once at the wedding but she seemed like a very nice lady. I have only ever been to the funerals of my grandparents so I'm not quite sure what the etiquette here is. With my grandparents I was there for the entire wake and the funeral and burial. My sister hasn't asked anything specific of us, just sent the obituary and the calling hours, so I'm not sure what is expected. Do I go to the burial or is that just for family? How long should I stay at the wake? What would be an appropriate amount of money to put in the card? Is there anything else I should be doing?

Thank you!