Cygwin - Cygnus for Windows - Linux based ported to Windows

Please provide some input; I can't find the information I need on the net to
complete my mission at hand. This issue is ongoing and needs to be
addressed, Thank you in advanced for any information you can provide for the
following:

PostgreSQL
How can I dump (backup) and restore?
How can I merge two PostgreSQL databases?

Example: Authoritative server copies from A -> B, Which will overwrite the
existing file on B. Need to merge one file to another then copy from A -> B.
Open the file as a XLS then import the other file, then you can sort.

Thanks a million for any help you can provide!
Joshua Yauger
System Administrator
Defense Information Systems Agency