Both Venus & Mercury.
It depends where you are. Some planets can be seen overhead at different times at latitudes up to about 24 or 25 degrees, but at higher latitudes they are never overhead. They are highest in the sky at midnight in the winter. At that time they are passing through the constellations of Taurus and Gemini when seen from the northern hemisphere, or Ophiuchus and Sagittarius from the southern hemisphere. That applies to all eight planets.
No, the zenith is never reached due to position of the sun and earth
It is not generally known how many planets are in each galaxy; it isn't even known how many planets are in our own galaxy, and will probably never be known exactly, due to its enormous size. However, according to latest observations, it seems likely that every star has several planets, at least on average.
The actual number of planets similar to the earth will likely never be known. The universe is simply too vast. However, it is likely that there are millions of similar planets.
In the city of Los Angeles, the sun reaches it zenith on the longest day of the year. That date will vary depending on when the summer season begins.
Planets compared to what? We will never know.
No. As of current known orbital data, the Earth will never be in a position to collide with another planet.
We can never know how many planets there are in the entire universe.
They didn't spend a "honeymoon" anywhere except perhaps Alexandria where they lived. The ancients did not follow that custom. Besides Antony and Cleopatra were never legally married in the first place.They didn't spend a "honeymoon" anywhere except perhaps Alexandria where they lived. The ancients did not follow that custom. Besides Antony and Cleopatra were never legally married in the first place.They didn't spend a "honeymoon" anywhere except perhaps Alexandria where they lived. The ancients did not follow that custom. Besides Antony and Cleopatra were never legally married in the first place.They didn't spend a "honeymoon" anywhere except perhaps Alexandria where they lived. The ancients did not follow that custom. Besides Antony and Cleopatra were never legally married in the first place.They didn't spend a "honeymoon" anywhere except perhaps Alexandria where they lived. The ancients did not follow that custom. Besides Antony and Cleopatra were never legally married in the first place.They didn't spend a "honeymoon" anywhere except perhaps Alexandria where they lived. The ancients did not follow that custom. Besides Antony and Cleopatra were never legally married in the first place.They didn't spend a "honeymoon" anywhere except perhaps Alexandria where they lived. The ancients did not follow that custom. Besides Antony and Cleopatra were never legally married in the first place.They didn't spend a "honeymoon" anywhere except perhaps Alexandria where they lived. The ancients did not follow that custom. Besides Antony and Cleopatra were never legally married in the first place.They didn't spend a "honeymoon" anywhere except perhaps Alexandria where they lived. The ancients did not follow that custom. Besides Antony and Cleopatra were never legally married in the first place.
If you are located anywhere on earth that's more than 23.5 degrees from the equator, then the sun can never appear at your zenith. If you're anywhere within 23.5 degrees of the equator, then the sun will appear at your zenith, or very close to it, twice each year.
The number of planets never seen could be millions, billions, or trillions. We just have never seen them.