It's not harder to enter the U. S. from Puerto Rico, or vice versa. In fact, it's the same as entering from one state to the other. Of course if you're not a U. S. Citizen or are entering from another nation, you would need to verify the laws of Immigration that apply to you.
Yes. Any valid state issue I.D. is valid for enter and exti Puerto Rico.
I do not think an Indian with a US visa needs a visa to enter Puerto Rico
None if you are a US citizen.
Generally, no. Mexican national must obtain a visa from the US Embassy or Consulate to enter any part of the US, including its territories, like Puerto Rico.
Puerto Rico is an US territory. Puerto Rico use the US dollar($). All citizens born in Puerto Rico are US citizens.
No, you do not need a passport to enter or exit Puerto Rico if you are a citizen of the United States. Puerto Rico is a territory of the USA.
Yes if you need a visa to enter to the US. Puerto Rico is an US territory.
No, it's a non-incorporated US territory (or colony, if you wish).
Puerto Rico.
Puerto Rico is a US Territory and its inhabitants are US Citizens! So, if they are US Citizens, any US citizen can live in Puerto Rico.
Puerto Rico
There is no President of Puerto Rico. Puerto Rico is part of the US, so the President of the United States is the head of state for Puerto Rico, as for the rest of the US.