Hosea is prophesying that Israel will be taken into captivity because of their sins. This is the result of having forsaken the Lord. There are some pretty serious consequences listed.
The phrase "gone a whoring from thy God" is pretty much what it sounds like. It is more symbolism using the bride and bridegroom analogy. Jehovah, the bridegroom, is married to Israel, the bride, but Israel was not faithful to the Lord. In this symbolic sense Israel is committing adultery (idolatry). But the word "whoring" sounds much worse. This may indicate that there were several gods or goddesses Israel was willing to worship. It could also indicate how quickly Israel would jump into a situation with worshipping a new god.
Regarding the "cornfloor", however, literally speaking, the "whoring" could also represent the following. Threshing would usually be a big event after the harvest. This process was a manual process of separating the seeds from the husk or straw. It was laborious, usually only done by men, and would sometimes take days. Men would often have prostitutes during this time.
The prophesy that "Ephraim shall return to Egypt" means they will return to bondage...specifically Assyria. The word 'bondage' is interchangable with Egypt here.
Again, saying that their offerings and sacrifices are not pleasing just means that they were not doing them the right way. In most cases, they were doing them perfectly by the letter of the law, but their hearts were not in them. It was possible for them to be perfect with the physical ordinances and offerings, but at the same time they were wicked people and their hearts and minds were not centered on Christ.
The prophets spoken of here, that are mad and fools, are the false prophets.
Comparing Israel to "grapes in the wilderness" and their fathers as "the firstripe in the fig tree" meant that at one point the Lord saw Israel as good (since the images used would be described as "good" or "choice"). They used to be righteous but now they are wicked.
This verse describes the lack of (or decrease of) conception, pregnancy and birth that will happen, possibly during the captivity. This is a terrible judgement for a nation that was told by the Lord that their seed shall be as the sands of the sea. Obviously they forgot the part where the blessing was predicated upon their obedience to the laws given to them by God. To us, this is a potential blessing we can also have, or like Israel, if we are not obedient we could receive the same fate.
This verse indicates that even though they've raised some or all of their children, even those raised children will be cut off from the Lord, and feel the consequences.
Here we see the term "revolters" again. A revolter was someone who lured their prey to a camouflaged pit or trap. Saying that Israel's princes (or leaders) are revolters is saying that their leaders are in a sense, spiritually hunting them. Hunting is basically likened unto killing. The leaders are pushing the people further towards wickedness and spiritual death.