The definition
obnoxious (adj.) very rude, offensive, or unpleasant : an obnoxious child; an obnoxious habit
is almost correct, but as commonly used, obnoxious also implies that the offensiveness is difficult to ignore. An obnoxious child is not just rude, but loudly or aggressively so. An obnoxious color or combination of colors is unpleasant but also intense or bright like the way the building in the linked article was painted:
I would rewrite the definition as
obnoxious (adj.) very rude, offensive, or unpleasant in a way that is difficult to ignore: an obnoxious child; an obnoxious habit
I don't know if I feel hatefulness toward an obnoxious person - I think it's too strong a word. I would describe it as strong dislike mixed with annoyance.
Generally, when "stand" is used to mean "is in a standing position", it is accompanied by a location:
He stood in the corner, sipping a whiskey.
They stood around the table, arguing.
She stood by the window, looking forlornly down the empty driveway.
Often this meaning will be expressed in the past continuous, using "was standing" instead of "stood" to unambiguously refer to the condition of standing, as opposed to the act of standing:
He was standing in the corner, sipping a whiskey.
When "stand" is used to mean "get to one's feet", it is either unaccompanied, or accompanied by an event:
He stood when she entered the room.
They stood as the speaker finished his speech.
"Now that you're here, I can finally leave," she said as she stood.
In my experience, stand up is rarely used for "be in a standing position" when it refers to a person; you are much more likely to hear it used for an inanimate object (especially one which is normally horizontal), and again it will most likely be accompanied by a location:
The bedframe stood up against the wall.
Most often, stand up is used for the action of getting to one's feet:
He stood up and stretched
As I approached, he stood up and reached to shake my hand.
Everyone stood up when the orchestra finished its song.
In your first two examples, people changed from sitting to standing when the president came in, and people changed from sitting to standing for the opening of the speech (they did not remain standing for the entire speech, but sat down again after only a moment or two).
Your given alternatives, "get to one's feet" and "rise", both unambiguously refer to the action of changing from a non-standing position into a standing position.
Best Answer
In English, the use of plural pronouns to refer to a single individual is commonly referred to as the "Royal We." It is extremely rare, and is never used by non-royal individuals, even extremely pretentious ones. You could use it as a humorous affectation, but it would be an extremely broad and quite unrealistic effect. It is so unusual that the effect would be more bizarre or delusional than pretentious, unless the person was actually claiming to be royalty.
A similar, more commonly seen pretentious affectation is for individuals to refer to themselves in the third person. For example, in an interview with Madonna, if Madonna said:
that would be an example of referring to oneself in the third person, and would be seen as extremely pretentious, but not as bizarre as if she said:
In your example, this would be something like, if the speaker was named Robert:
Another, milder, pretension, at least in American English, would be to use the pronoun "one." In your example:
The pronoun "one" is considered formal and somewhat archaic even when used properly, to refer to an indefinite person; when used to refer to oneself, it is also considered highly pretentious.