When looking at a series of flags in the USA the flag of the United States of America should always be on the left. Another way to look at it, if you were the flag this would be the flag's right. On a stage the US flag should be on the left of the stage from the audience view, to the right hand of the speaker. Again, the flag is positioned on the flag's right.
If there is a row of flags the US flag should be in the center on the tallest flag pole.
In the United States, the flag is traditionally displayed on the right side of the room when facing the front. This means it should be positioned to the speaker's right when addressing an audience. If the flag is being displayed with other flags, it should be placed at the center and at the highest point.
Respectfully never touching it to the ground. It should always be cased when not in use. There's a lot of flag etiquette rules also as far as how to fly it properly (ie. with other flags, vertically, etc)
When displaying the U.S. flag alongside state flags on a flagpole, the U.S. flag should always be positioned at the top of the pole. If multiple flags are displayed on separate poles, the U.S. flag should be placed on the center pole if it is in the center, or to the right of the other flags if arranged in a line. This positioning reflects the U.S. flag's status as the national flag and shows proper respect.
The ground the ground
No - "The flag should never touch anything beneath it, such as the ground, the floor, water, or merchandise."
They fly a different flag, because they are a different country, now if they were the same country, they would fly the the US flag.
The U.S. flag should be flown from dawn to dusk. If flown at night, it is to be illuminated.
It would be respectful, but is not required.
Yes, it is legal in the US to fly a US, or other flag, from your car. Many people do that.
Any state flag should be flown below or level with the US Flag, but never above it. If it is on the same level it should be on the right, this includes Texas. The rumor that Texas is the only state that is allowed to fly at level with the US Flag is just that a rumor and an urban myth.
No flag can be flown the American flag when on American soil.
According to the US Flag Code, the US Flag should be larger in size and (if flying on the same pole), at the top of the pole. If flying the American flag with a state flag, the American flag needs to be on a taller pole than the state flag and displayed on the flag's right side. If flying them on poles of equal size, then flying the American flag on the flag's right side is correct.
No; at least not in the US. On diplomatic situations however, both should be at the same level (e.g. outside the United Nations).
Texas
Technically, they are on their own soil, so no, they don't have to fly our flag. Just as our embassies don't fly their flag.
It could, but it would be disrespectful.
It is legal to display any flag in the US. This is a matter of freedom of symbolic speech.