Hi Mahmoud! Welcome to the forum.
I can answer your questions about the US.
1. The candidates basically say "I'm running for President!" (though they do have to fill in some papers,) and generally they are already a member of a party. Afterward, elections are held in single states in which voters determine which candidate they believe would best represent their respected party. Once a candidate collects a certain number of delegates (people who go to the national party conventions every four years) they win the nomination.
2. Some candidates have a party (Republican, Democrat) but some don't. There are also smaller parties (Libertarian, Socialist, Constitution) but they aren't expected to win much, as they are virtually unknown.
3. No, only one Presidential candidate may be nominated. The party nominates a Presidential and Vice Presidential candidate.
4. I think you're referring to the cabinet. When the new President comes in, he or she picks people to serve as the head of a certain department. There are several departments (Treasury, Health and Human Services, Transportation, etc.) in which many different people serve. The people picked by the President to serve must first be confirmed by the Congress in a majority vote.
5. It's not viewed as a bad thing in general, but a lot of people think it's bad. Essentially, if the President and Congress are both of the same party, the Congress can just propose legislation, pass it right through and the President signs it into law without opposition.
I hope I answered your questions well enough!
Cheers,
20RP12
