Conversion from Sybase

Hello,

I am evaluating the possibility to port several applications from Sybase
ASE. Reading the PostgreSQL manual, (and getting a very good feeling about
PostGreSQL, I must say) it seems reasonably feasible but I have still some
doubts about the following:

-Case sensitivity : I have found a mention of case sensitivity/insensitivity
but have not found how to control this. For selects using or not an index
-Temporary tables: in Sybase I often use temp tables: tables created 'on the
fly' during the course of a stored procedure. This allows for some havey
processing to happen on the server side before returning results or
minimising the number of updates. Is it possible to create
-I often use the variable @@spid which , in Sybase, corresponds to the
current process id, this allows me to partition work tables when temporary
tables cannot be used in Sybase : one cannot create temp tables from within
a transaction. This is particularly useful to me when several "system" or
unattended task run. All my program connect using the same user , which
makes sense in a context of automatic interfacing between applications, run
via a cron job. In that case I cannot use a user id to achieve what I need.
-Multi-database queries or at least possibility to call a function in
another database. I often use this to build interfaces between systems. I
believe this is not possible in PostgreSQL.
-Multi-server (RPC) comminucation. clearly the answer to this one should be
no if the previous is not possible either.

Could you point me to a place where I could find the answers to these
questions (if you do not have the answer readily available :)

thanks in advance

Didier