You need a passport and an entry visa if you are entering Mexico from any country other then the US.
No. People with European passports are allowed to enter Mexico without the need for a visa.
No. People from most developed countries don't need a visa to enter Mexico, just the passport.
They will need a visa to enter the United Kingdom in order to enter Northern Ireland.
No; Latvian nationals don't require a visa to enter Mexico; all they need is their passport.
Yes
No. Having a visa for the US doesn't grant you the possibility to enter Mexico; you need the corresponding visa from Mexico.
No, you don't need any.
No; only diplomatic staff requires a visa to enter Mexico.
Yes they/you do.
Yes.
No. American citizens don't require a visa to enter Mexico. All you need is your passport.
You don't need a visa to enter Mexico if you are an American, Canadian or European citizen. If you, however, are from other country, even when entering from either territory you need to have a visa issued by the Mexican government.