Yes.
If they do so, you'll probably be given a test at the station just to back up the officer's statement and make it easier to convict you; if there's no test, a halfway decent lawyer should be able to argue the charge down to "disorderly conduct".
Yes, a police officer can arrest you for being publicly intoxicated (PI) without running any specific tests if they have reasonable grounds to believe that you are intoxicated based on your behavior, appearance, or other evidence. However, in some jurisdictions, a field sobriety test or a breathalyzer test may be required to establish legal proof of intoxication for prosecution purposes. The specific procedures can vary depending on the laws and regulations of the jurisdiction in question.
The officer can ticket you for the traffic violation, he or she can arrest you if there are mitigating circumstances.
An arrest refers to the lawful deprivation of the freedom of an individual by a peace officer. A police officer may arrest a person if he reasonably believes a crime has been committed without a warrant.
Trespasser is the term for this. This is illegal and you can be arrested for it. A police officer will not usually arrest someone the first time they are caught trespassing. But it is up to the police officer to arrest or not.
Yes, of course. An arrest warrant is a command from a judge to arrest a person. Usually a police officer has no choice and must arrest.
yes
No.
A police officer making an arrest
No, a police officer cannot issue a warrant for your arrest only a judge or court magistrate can do that.
A person is "under arrest" when a police officer charges them with a crime and chooses to take them to the police station to be processed for it. For example, if someone commits a crime, they are technically under arrest when a police officer witnesses the crime or has a warrant for the arrest and tells the criminal "You are under arrest." Typical procedure after this is to put handcuffs on the criminal and read them their Miranda rights (you have the right to remain silent etc). Handcuffs alone do not mean arrest, but i'm pretty sure its illegal for a police officer to handcuff someone without grounds to arrest them. As a side note, the person doing the arrest does not have to be a sworn in police officer. In Citizen's arrest cases, anyone with arresting powers like a bounty hunter can also place someone under arrest.
It does not seem reasonable or possible.
The police officer decided to arrest the suspect after reviewing the evidence.
The officer can only make decisions on whether to arrest, cite, or not to arrest, referred to as officer discretion. The officer cannot (honestly) promise leniency of a charge because they do not have that authority. Charges are filed and issued by a prosecutor, not a police officer. Any statements given to a police officer based on a "promise of leniency" without the prosecutor's cooperation will be considered coerced and inadmissible.