In otherwords can this Spark build also act as a Hive client?
My instinct is that it will but I don't have CDH 5.4 and can't immediately confirm.
Is there a fast answer for this?
Hive on Spark uses Spark as the execution framework like MapReduce is the execution framework.
Spark SQL uses Hive dependencies but that side is not supported. Hive in CDH is newer than the Hive Spark is designed against and there are parts that do not work against the new release of Hive. Some parts will work others will not.