Not really sure what you’re asking here. If you have an extension of stay based on a particular reason and that reason finishes then the extension of stay finishes that day. Marriage, Work, etc.
The only difference is that if it’s based on marriage and the spouse dies then you can stay until your extension finishes. You’d then either need to leave or switch to another reason for an extension.
Some people print and laminate the pdf file. I’ve seen posts from people with a full A4 print or ones printed passport size and laminated.
It’s not technically necessary to have a printed version as the IO should be able to see on their system that you have a DTV but it just is a help to show you have one to get the right stamp.
ALWAYS check the stamp they give you. Mistakes happen, but the onus is on you to check.