Effectiveness of spaced learning when the data have personal meaning
I'm not sure if personal relevance of data has been studied directly, but this factor seems related to depth of processing [Wikipedia link A], which improves memory encoding. I'm not aware of any research on an interaction between depth of processing [Wikipedia link B] and whether learning is spaced (as an experimentally controlled variable). I hope others will have more info for you on these questions.
Relatedness of data has a clear effect on learning and recall. Chunking is a mnemonic technique that capitalizes on relationships among data to facilitate info-reconstructive processes in memory. This can even be performed on ostensibly unrelated data using elaborative rehearsal. (See also depth of processing link A.)  Example methods include combining disparate elements in a narrative, or associating them with landmarks using the method of loci.