1. They are of course very familiar with the Emerald Isles, considering how often their raiders have assaulted its holdings...until the recent colonization of part of its shores by a particularly ambitious chieftain complicated that situation politically.
During your diplomats time amongst the Caribou, they asked for their knowledge of other cultures, if they had encountered any. The Kings and Dukes expressed little knowledge, their focus and attention upon matters closer to home, but the sea-faring merchants of the coastal settlements spun tales of vast grasslands and burning deserts in the lands beyond the grey mountains that form a border between Olenia and whatever lies to their South. Supposedly these lands are inhabited by a great many races, from black and white Equines to felines that walk upon two legs. Attempts to trade with these peoples were initiated, but were more often than not ruined when a band of aspiring Vikingers got wind of the new lands and decided to pay them a visit.
The potential trade partners weren't very welcoming of Caribou after that.
As for the lands that lie to their East...
They speak of a mighty blizzard that blows eternally, of winds that cut like knives as the air itself turns to ice in one's lungs. They speak of a people that live beyond this barrier, like and unlike the Caribou in ways none can properly articulate. Their origins and nature are a mystery, but plenty of speculation and rumors exist, for if any Caribou has traveled through the blizzard, then they have never returned.
2. There are four primary Petty Kingdoms, with a number of smaller counties and baronies beneath them. It is not unheard of for a count, baron or chieftain to switch their allegiance from one king to another if they feel it suits them, but this almost always ends in a war between the aforementioned kings, so this occurs rarely.
3. They worship a Pantheon of god's not too dissimilar from that of the Ancient Empire's, with a little bit of Neighponese-style nature spirits thrown in. They are rather curious in that they rarely outright reject the existence of another culture's deities, usually accepting them as aspects or "lost relatives" of their own gods. Many Caribou are spiritual rather than religious, and while there are plenty of shrines, temples and holy places scattered throughout Olenia, there isn't any religious hierarchy uniting or coordinating them. In addition, it is not unheard of for particularly religious Caribou who have chosen to devote themselves to a singular god of the pantheon to engage in conflict with those who have pledged their lives and service to "the wrong Diety", though this is rare and most other Caribou look down on such behavior.
4. The Caribou, like all other cultures, suffered under Discord, though if their oral tradition is to be believed they suffered more than others. Legend says that all Caribou were once united into a single, prosperous kingdom, blessed with fertile fields and warm waters. Then Discord came, altering the land and turning the people against each other. Now they are fragmented, their cold and harsh lands a bitter reminder of all that they have lost...or so their stories go. As far as you can tell, they don't keep many written records. Regardless, they survived under Discord's rule and most other races did: hiding from his attention and riding out the storm of madness that engulfed the world in those years of insanity.
5. It would take a true Hero to unite the varying kingdoms and cults that make up Olenia, as deadly upon the field of battle as they are adept in the halls of power and intrigue. It would need to be a truly legendary figure, one whose name would echo throughout time even before vying for the grandest of thrones.
6&7. Due to the fact that they live in fantasy Scandinavia...very little. Enough to feed themselves, sure, but there's a reason they always went after the granaries and store houses of the Emerald Isle Diamond Dogs. Thankfully what foods they do grow are hardy, and they are both capable of and willing to eat grass, though they aren't capable of subsisting off of that entirely for long periods. Turnips, Onions, Cabbages, Leeks, Barley, and other hardy food crops are staples of Caribou diets, and some even raise chickens and geese for their eggs.