dump means it contains information about the ouput of the job in spool.
when a job abended or to get the information about the status of the job
it is useful.
the storage of dump you can specify in job by using sysout .
for ur 2nd question
when a dataset created then it should be catloged in user catlog or in vsam catlog also the informaiton about the dataset is maintained in VTOC.
it contains information about the dataset.if you want to know the information about the dataset u can IDCAMS utility and specify in
sysin dd *
use LISTCAT ALL
it will give the entire information about datset.