Sharing with free accounts when cards have premium features such as custom fields

[robert hindle]

If I have a standard or above account and share a board with someone on a free account - will they be able to contribute to that board, such as add or move cards?

If a card has paid-for only features, such as a custom field, will those users be able to update those custom fields, or will they be locked due to their account level?

Is there granular permissions, so someone can add, edit or move cards but not create or delete lists?

[Michael Pryor]

Yes. If you had someone to your board and the board is in a paid Workspace then everyone on that board will see the paid features. 

[Jack Brickey]

Only users within a given instance will have access to anything in the instance.