I really can't be of much help with the replication configuration, but you should be able to solve the first issue:
I still can't see the oracle provider under LinkedServer---->Providers within Sql server management studio.
Is this still an issue? If it is, I'd first solve that one.
Check for permissions on Oracle directories for the sql service account in use:
BOL: "The account under which the SQL Server service on the Distributor runs must be granted read and execute permissions for the directory (and all subdirectories) in which the Oracle client networking software is installed."
Hrvoje Piasevoli
Hrvoje Piasevoli