Thanks for your questions!
This is very interesting. From a product point of view, this means we can create custom transactions (or business logics) inside a local validator node? ex : if today is monday send 1 libra to XYZ account from QWE account ?
You can create custom transaction logic, but it must still be submitted to a validator node. There is no event loop inside the Libra blockchain; every state change must be triggered by the execution of a transaction submitted to a validator.
Compared to ethereum BC, how this module will interact with external world (oracles?)
It’s crucially important that transaction execution is both deterministic and hermetic. To ensure this, Move programs cannot interact with any code or data that is not either (a) on the Libra blockchain or (b) in the current transaction. So any interaction with the outside world must occur via an ordinary transaction.
Existing blockchain platforms have the same limitation. Oracle services have clever ways to work around these limitations. The same strategies that oracle services use for existing platforms should also work on the Libra blockchain.