>> If there is no space for new inserts in the database, and after that if I delete some rows, can I insert new rows immediately?
It depends on your PCTUSED setting. Ifthe deletes moved the block onto the freelist, then "yes":http://www.dba-oracle.com/oracle_tips_PCTFREE_PCTUSED.htm
>> What is the diffrence between shrink and alter table move
Alter table move - The alter table xxx move command moves rows down into un-used space and adjusts the HWM but does not adjust the segments extents, and the table size remains the same. The alter table move syntax also preserves the index and constraint definitions.
Alter table shrink space - Using the "alter table xxx shrink space compact" command will re-pack the rows, move down the HWM, and releases unused extents.