Mantenerse en contacto con nosotros.
If you mean it as command i.e. "Stay in touch with us" as opposed to He wants to stay in touch with us", the Spanish command is "Mantente/Manténgase/Manténganse en contacto con nosotros" (tú/Ud./Uds)
No, it did not touch Spain or the US, only the Spanish Territories in the Northern Hemisphere.
No,H.U. is going to stay in touch of the U.S. and travel around the world.
United States in Spanish is Estados Unidos.
you say: "no nos olvides"
Los Estados Unidos
Dólar americano.
If you wan to say 'join us' in Spanish language, you will need to use the words: 'Unete a nosotros', this is if you want to say it in imperative form.
Los profesores nos ensenan (en espanol) = The teachers teach us (in Spanish)
los estados unidos
de los Estados Unidos
Ella nos da.
Translation: Nos quieres.