Are there any recommended SQL Server 2008 R2 instance features for Sharepoint Foundation 2010 please? Is there any specific SQL feature that should be enabled please?
You just need the Database Engine Services (not even its children features). The management tools (basics) are recommended to quickly & visually manage your instance but they can be installed on a separate machine.
Anything else is optional and not required / used by SharePoint Foundation 2010 and it's always a good practice to limit your installation to the few features that are mandatory.