Sync - not sure how it works - several questions

[#1]

1. How do I get a photo in Lightroom Mobile to show up in Lighroom Classic or vice versa?
2. If I delete photos in Lightroom mobile, will it be deleted also in Lightroom Classic?
3. I have photos that are said to be 4032x3024, 2.2 mb, on Lightroom Mobile. But when shared via gmail or Flickr, the size is less than half (700kb). Why is that?

I am aware that the answer might be obvious to some, but I am struggling to understand... Thanks.

[#2]

Hi Bjorn,

1. With sync on in Classic all photos in LrM will sync to the cloud and down the folder set in Classic's preferences. To sync to LrM from Classic, would you create Collections and sync them (this would only sync lower res Smart Previews).

2. If the file has synced to Classic then you can delete from LrM and the photo in Classic will not be deleted.

3. What happens when you export to a different location? Is it the same?

[#3]

Thanks!

Regarding last question: it seems like that, yes. I have tried to share to Flickr and gmail.

Bjorn