Shutterstock used to break phrases into the constituent words. Am I right in thinking that this has now changed and that the search there now allows for multiword phrases ? How do people here recommend keywording phrases ? Is: sports, car different from sports car ? Can a single keyword effectively include a space character ? What about the plural form, would you also need to add sports cars ?

Is Shutterstock okay with comma separated IPTC keywording ? I was reading a thread from last year on their forum in which people were reporting that all of their comma separated keywords ended up being imported as a single keyword.

Any best practice tips with respect to IPTC keywording for Shutterstock ? I know that plurals are no longer normally required. Are their exceptions? Please feel free to constructively expand this into a general thread about Shutterstock keywording.

... the description is also used as keywords.

Worth watching out for, especially in Editorial.
E.g. if you had a hypothetical editorial photo of a crowd 'waiting for the arrival of Barack Obama/Justin Bieber/a solar eclipse/whatever' and described it accurately as such, then it might show up in a search for BO, JB or 'eclipse' - al mosst certainly not what the searcher was looking for.
That's a trap for the unwary at Alamy too (where the caption NOT the description is searchable).