Moving from Sybase to Postgres - Stored Procedures

Hi,

I am moving from Sybase to pgsql but have problems with stored procedures.
The typical procedure uses

a) named parameters,
b) local variable declarations and assignments
c) transactions
d) cursors, views, etc.

I can't seem to find these things in the Postgres function syntax.
Procedures can be as long as 20-250 lines, performing heavy data
manipulation tasks, running from a few seconds up to several hours. Database
size is approx. 20GB.

Functions in pgsql are very limited compared to Sybase procedures, so I'll
have to find a workaround somehow. Perhaps somebody can point me to examples
or hints regarding this issue.

Thanks in advance!

Andre