trigger bugs ? and suggestions

Hello all

Follow up my previous post and the respons given by Andrew Sullivan,
I make a lot of tests and first problem the function _PG_fini are never
called it is a bug ?.
This is a big problem for me because I want to cleanup the data managed
by my trigger.

second problem I cannot detect from a trigger the kind of call (row or
transaction) I suggest (if it's possible) to add a trigger event like :
begin start, begin end copy start copy end or something like that.

and finally if the trigger run inside a transaction like copy or
begin/end I cannot read the modifications make by my trigger in the same
session.
it is possible to have a special select like select_uncommited data ?

regards

Guy