There are two questions here:
How many people? It takes 10 people to hold a full service, so that's the minimum. The maximum is however many people will fit, which depends on the size of the room.
When were the first synagogues designed? We know that, by the time the Gospels and letters of Paul were written, there were synagogues all over the Roman occupied Jewish world and also synagogues elsewhere in the eastern Roman Empire, all the way to Rome. So synagogues were developed before that time. The institution of the synagogue may have emerged during the Babylonian captivity. The first purpose-built synagogue, that is, one that could claim to have been designed, was therefore some time between the Babylonian captivity and the time of Jesus.
The number of people in a synagogue varies depending on the size. However, for prayer there are usually at least ten people.
There are synagogues of many different sizes. The largest synagogue in the world, the Belz Synagogue in Jerusalem has nearly 6000 seats. There are numerous synagogues with only enough space for 10-15 people, where the congregation is small.
Jews study many different things in a synagogue. Here is a short list:Jewish laws and customsEthicsHistoryMusicand almost any other kind of secular learning
To dedicate, plan and build a synagogue, any number of people is okay. For prayers, however, religious Judaism requires that ten men be present.
In the synagogue, the entire book of Esther is read (usually in Hebrew, but not always) and each time the villain Haman is mentioned by name, the children in the congregation use noisemakers to "drown out" his name. Many people also dress in costumes.
For His time, Jesus was politically incorrect. He angered many with His teachings and was accused of blasphemy, which was punishable by death.
there are 100 windows on a synagogue
No one knows how many synagogues were in Jerusalem at the time of Christ. The word Synagogue comes from two Greek words. The first is syn or sun which means together. We have the word synthesis which means putting a lot of stuff together. The second part is agogue, or place. Any time 10 men would meet for worship, you could have a synagogue. Women did not count. A separate building could be used as a synagogue. But empty room on a house could be used as a synagogue. And least common, a house could be used as a synagogue. Anyway, all such records were burned in 72AD.
The Hebrew is the language of Jewish prayer and liturgy. All Jewish prayer books contain Hebrew. Some synagogues are also decorated with Hebrew letters or words, but it depends on the synagogue.
Yes, there are many thousands of synagogues in the world.
There is no required position for the Star of David in a Jewish synagogue. In many synagogues, the Star of David is positioned towards the front, but this is not a requirement.
The word synagogue does not appear in the bible. Synagogues did not exist at the time the bible was written. In the historical period that the bible writes about, Jews worshiped at the temple, not the synagogue.