7.1 surround to 5.1 surround to stereo general questions

1. If I design for 7.1 and render a final product, will it automatically work in a condensed sense on a 5.1 system. How about 7.1 or 5.1 to stereo?

2. In Adobe Premiere Pro 2017, what is the correct procedure to initiate a 7.1 new sequence when in the dropdown it shows 5.1 and multichannel as options?

3. How would I automate pan as well as front and back for 7.1 when I can only see a tray for 5.1?

4. I have been using image sequences that are default set to stereo. Can I simply copy and paste the finished edit into a new sequence for 7.1 design?

Any other tips?

Thank you.