We find the Hebrews forming a calf to worship less than two months after they were rescued from Egypt. Ex 32:4,5.
Micah's graven image and molten image were formed during the times of the judges, back in the days when Israel was still conquering the land, years before Israel had a king, even years before Jerusalem was their capital.
Judges 17:1 And there was a man of mount Ephraim, whose name [was] Micah.
Judges 17:4 his mother took two hundred [shekels] of silver, and gave them to the founder, who made thereof a graven image and a molten image: and they were in the house of Micah.
17:5 And the man Micah had an house of gods, and made an ephod, and teraphim,
17:12 [He took in a wandering Levite]And Micah consecrated the Levite; and the young man became his priest, and was in the house of Micah.
Judges 18:1 In those days there was no king in Israel: and in those days the tribe of the Danites were looking for land for their inheritance to dwell in;
Starting in verse 18:11 six hundred Danites set out to conquer territory.
On the way they passed by Micah's place. Five of their men (18:18)went into Micah's house, and fetched the carved image, the ephod, and the teraphim, and the molten image. They talked the Levite (whose name was Jonathan a grandson of Moses) into joining them.
They went on to conquer Laish, And they built a city, and dwelt therein.
18:29 And they called the name of the city Dan, after the name of Dan their father, who was born unto Israel: howbeit the name of the city [was] Laish at the first.
18:30 And the children of Dan set up the graven image: and Jonathan... and his sons were priests to the tribe of Dan until the day of the captivity of the land.
18:31 And they set them up Micah's graven image, which he made, all the time that the house of God was in Shiloh.
Answer to question #1 Yes, it was the same idol AND additional objects of worship that the Danites stole from Micah.
They SAID it was for the worship of God, but everything they did was in direct violation to God's commandments.
The wilderness tent and its services were in Shiloh where the prescribed worship took place, until David moved it to Jerusalem. The Danites could have gone there to worship.
When Jeroboam around 922 -901 BC - chose to set up an idol at Bethel and Dan, he essentially inherited the dynastic priesthood of Jonathan that continued to exist until the Assyrian captivity (according to Judges 18:30) in 723 BC.
Was it the same, or was it different?
1340 BC to 922 BC is a long time, things change in 400 years, yet some things stay the same. It had gained a strong foothold and Jeroboam took this to much greater heights!
He set up one of the calves at Bethel on the way to Jerusalem. The other one he set up at Dan.
Tel Dan excavation has uncovered the Tel Dan Cultic site. It was quite luxurious.
"The Sacred Area or temenos at Dan is a large complex over a half-acre in size. The central open-air platform of the Sacred Area went through three phases during the Israelite period. Biran has identified the three phases of the platform as Bamah A of Jeroboam 931 BC, Bamah B Ahab 874-853 BC, and Bamah C of Jeroboam II 780-742 BC . In any event it is clear that this entire area at Tel Dan was an important Israelite cultic center.... the archaeological evidence suggests that a large, open-air platform was used, that there were altars, incense offerings, votive offerings involving figurines, and some kind of water purification or libation rituals." (The Remarkable Discoveries at Tel Dan, John C. H. Laughlin, BAR 07:05, 1981)
The space enclosed by the four walls was filled with basalt stones, forming a wide, flat platform. On the southern edge of the bamah, facing the town, a monumental flight of steps eight meters, or twenty-seven feet, wide was uncovered, built directly against the outer wall of the bamah (Fig. 13 ); this stairway is in part superimposed over the earlier masonry. Pottery collected from the steps points to a date in the mid-9th century B.C. A number of soundings carried out on the bamah, as well as remains of an earlier flight of steps apparently built before the construction of the ramparts, indicate that some structure, perhaps of a cult nature, existed here already in the Middle Bronze II age.(Tel Dan, Avram Biran, Biblical Archaeologist, vol 37, 1974 AD)
Are we seeing in this passage the roots of the Golden Calf tradition at Dan?
It was already done before -- using a calf or ox, thinking of it as a visible symbol for God (at Sinai), but there it was squelched.
There is evidence that this counterfeit calf worship started to gain a foothold in Israel, with the Danites and the apostate Levite Jonathan in 1340 BC. There is evidence the site in Dan could be the very same place where Jeroboam set up his calf. The worship was greatly enlarged and made the state religion by Jeroboam, and was followed by all the successive kings of Northern Israel.
This may well be the reason why the tribe of Dan is missing in the list in Revelation chapter seven.
Dan shall be a serpent in the way, a horned snake in the path, That bites the horse's heels, So that his rider falls backward. Gen 49:17
Jeroboam drove Israel from following the LORD, and made them sin a great sin. 2 Kings 17:21
The "sin"? Their worship had many similarities to the worship God ordained. But it was NOT what God ordained. It was a counterfeit.
That's one thing that struck me while visiting ancient temples in the Mediterranean lands. They all had similarities in design to what we picture concerning the Jerusalem temple.
They even had holy and most holy places, and altars, BUT the god in their supposed sacred spot was a different god.