Please review - Assets Migration Guide Thanks

No this not available OOTB. However, if you navigate to asset details page and select settings from action bar you can change schema which would display respective schema on page.Although i hope this should be done at project level.Thanks

It was part of sample content of Geometrixx which is still available and you can download from Package Share. Since we did not shipped that with 6.3; more info here We.Retail Reference Implementation so you need to install that to review sample implementation.Thanks

Asset share pages. Not related to Link SharingThanks

I don`t have further info as you can create one sample one and move and play with that property and see.Thanks

If you are not on latest Service Pack and Cumulative Fix Pack on 6.1 we recommend one as we have done lot of improvements in this area specially in Touch - UI. You might want to review this - Adobe Experience Manager Help | Release Notes: AEM 6.1 Cumulative Fix Pack Thanks,Gaurav

AFAIk and AFAIU in case of different formats or selecting assets from different locations it shows default schema.Thanks

Have you reviewed this already - How Does Asset Expiration Work in AEM 6.1

This has been discussed here thanks

Expiry is at author end and will add label of Expired on thumb letting users know this is something which should not be used at author end. For publish end this off time is recommended - Dam Assets Ontime and Offtime Behavior along with expiryThanks,Gaurav