>1. How can view, search the table that slony hold all its paths, nodes,

>sets etc?? Can I look in it with postgreSQL?
 
To simplify things, here is a query that will return the name of 
all slony_schemas you have created.

SELECT nspname AS "Schema_Name"
  FROM pg_namespace nsp
  JOIN pg_proc pro ON pronamespace=nsp.oid AND proname = 'slonyversion'
 ORDER BY nspname;

To get the names of all slon sets

SELECT * 
     FROM _your_slony_schema.sl_set;

Likewise, to get info of all tables replicated:

SELECT * 
     FROM _your_slony_schema.sl_table

and sequences

SELECT * 
     FROM _your_slony_schema.sl_sequence;

>2. Is there any request in slony that will tell me when slave database 
>has been totally replicated. I mean process of replication finished
with 
>success and both master database and slave database are the same???

I always send the output of slon to a log file:

slon -d1 -pslon_node_1.pid $USCUSTREP "dbname=$MASTERDBNAME
user=$REPLICATIONUSER   host=$MASTERHOST port=$PGPORT" > slon1.log &

Then you can grep through the log to check for errors:
eg:  grep ERROR slon1.log

Likewise to verify when a slave has successfully finished subscribing:
grep copy slon1.log