There are two reasons, one didactic and one a pun: First, on the first Passover, the book of Exodus says that God "passed over" the houses of the Israelites that were daubed with the blood of the first Passover sacrifice, entering all other houses and killing the firstborn -- this was the final of the ten plagues that God brought upon Pharoh and the Egyptians for not letting the Israelites go.
The second reason, the pun, is that, entirely by coincidence, the name Passover is very similar to Pesach, the Hebrew name of the festival. In other European languages, this pun doesn't work, so Passover are known by names that are simply transliterations (sometimes ugly, sometimes accurate) of Pesach. To add to the confusion, in some languages, Passover and Easter are known by the same name.
Yes, because Passover is a Jewish festival. see also:What_do_Jews_do_when_celebrating_passover
There are always Jews who celebrate Passover regardless of the location or circumstances. Jews celebrated Passover in the ghettos, and then in the concentration camps.
Irish Jews celebrate Passover the same way as Jews all over the world.
There is no such thing as a "reformed" Jew. It is called "reform Jew". Reform Jews celebrate passover as a commoration of the exodus of the ancestors of the Jews from Egypt and into freedom, which is the same meaning passover has to Conservative and Orthodox Jews.
German Jews celebrate Passover, too.
Passover is usually only celebrated by Jews
The same way that all other Jews observe Pesach (Passover).
Jews in Sweden celebrate Passover. The question is complicated by the fact that the name of Passover is Pesach in Hebrew, and this is easily confused with Påsk, the Swedish name for Easter which is pronounced similarly enough that Swedish Jews sometimes have difficulty explaining that no, they are talking about the Jewish festival, a festival that has nothing to do with the resurrection of any messianic figure.
Jewish people celebrate Passover to celebrate their people's liberation from slavery. The holiday celebrates when Jews were freed from slavery in Ancient Egypt.
On festivals such as Passover, wine is had.
Muslims do not celebrate Passover; Jews do. Regardless, Passover does not command any person to respect any religion; it is a story about how the Israelites escaped Ancient Egypt through an act of Divine Deliverance.
Jews still celebrate Passover to this day.