Every elible voter within the state that the Senator is running votes is able to vote for the Senator. Not the entire United States as in a Presidential election.
All registered voters are entitled to vote for the state's US senators. Of course they never have 100% turn-out and there is always the possibility in any election that some voters will be illegally denied a chance to vote. That is why both parties assign people to watch the polls.
Citizens of the US can vote for president in the US.
Senators can vote like any US citizen for the president. They do not have any special powers in that regard.
Democrats hold the state legislature and the republicans have the Governor's mansion. The state tends to vote for democrats in National elections and the majority of their US Representatives are democrats as well as both their US Senators.
true
Each state has 2 senators each, regardless of population.
Yes, this is allowable.
True
The vice president of the US , who presides over the senate, can vote in this case.
To pass an amendment in the United States, it requires a two-thirds majority of both houses of Congress. There are 100 senators in total, so at least 67 senators would need to vote in favor of the amendment for it to pass.
The US government is part republic and part democracy. In a true democracy the people directly vote on laws - there are no representatives or senators. In a true republic the people vote on representatives who then vote on senators. So America is part of both. (The founding fathers originally intended America to be a true republic, but that changed in 1913 when the people were allowed to vote directly on senators. If you read the reasons behind the founding fathers' choice, a republic seems like a better idea.)
The vice president of the US , who presides over the senate, can vote in this case.