1. "Oracle Export can be done while the exported DB is open.
Therefore, Oracle Export can be used as an alternative On-line Hot backup"
Is this correct??

>> NO. Oracle Provides logical and physical backup mode. Export belong to the logical back and the hot backup belong to Physical one.
Export can not be considered as alternative to the physical backup because

1. incase of your db crash u will have to recreate the database
2. time take to import is much higher than that of hot backup.
3. U can not go for point in time recovery.

When using Oracle Export to export the "Full DB", instead of export to one big .dmp file,
how can we export to several smaller .dmp files with the same size (ex:1GB each)??

>> u can use FILESIZ parameter to restrict this

3. " in a DB with inconsistant Database files, we can export the entire DB and then import it back. Oracle will then see these Database files as consistant"
Is this true?? and how come after export and import Oracle will treat them as consistant??

>> NO. This is not True