Re: Sheltering Criminals.
Absolutely, that's why embassies have their special legal status - to protect the citizens of the embassy country from being persecuted by the host country if they disagree with the host country's policies.
No it's not. Embassies are there to allow communication between governments. Their immunities are provided in order to facilitate that. The Vienna Convention, which is the international law in question, says that they are not to be used for other purposes.
They are not there to circumvent the judicial system of their host country.