there is no relationship between HANDLE ABEND and (RESP & HANDLE CONDITION) commands, the former is used to handle abnormal termination exit and the later for conditional handling.
Now, and RESP & RESP2 (for finer condition details) implies NOHANDLE condiion so if you have RESP with every API command and no command can return same RESP code for multiple conditions then you can go away with handle condition or what I would suggest is to also use RESP2 for better handling.
About HANDLE ABEND processing this command would not be able to handle some system abends like S0C4 abends. Also use this command with caution in case original ABEND codes are required for debugging the application.
Hope this helps...