Immigration in the Tondene Empire

The Tondene Empire is a large country encompassing an area almost the size of the continental US, and including almost all of the sentient races on the planet (Humans, Orcs, Goblins, Elves, Dwarves, Hobbits, Aarakocra...the only race they haven't absorbed are the Klernak'thasa, the race of reptilefolk, and only because the borders of the Tondene Empire doesn't include the deserts where the reptile folk lived.) As a result of this, they are probably the least racist of the countries on the continent, as they were forced to deal with inter-racial conflicts for most of the history of the nation. There is still quite a bit of institutional racism, because people are people and you can't stomp out idealologies completely. Most of the governing is done locally, at the duchy, county, or city level. The highest levels of the government ("federal" level, I suppose we could call it) reign mostly by benevolent neglect, setting only global laws or resolving conflicts between duchies.
Stance on immigration: When an immigrant is detected (there is a vast area within the borders with very low population density, and even with magical aids to increase harvests and food production, it's still basically medieval in technology) they are detained and questioned by the authorities. If they are not some kind of spy or saboteur, or some other danger to the Imperium, they are released and given documents to show that the authorities have authorized their presence. Citizenship can be attained by registering at the city level (which often gets passed up to duchy level) and living in that local area for at least a decade (less for Aarakocra or Goblins, who have shorter lifespans). Criminal acts will make getting citizenship more difficult, although bribes can often smooth things along. Corruption isn't unheard of.
How often is there immigration: Occasional. It's not a lot; most countries have enough space and the population densities are low enough to not be much of a driver. Political or social drivers are more common, but even these are fairly minimal, especially since there may be language differences. This is mostly a human problem; there are two Elven languages (Quenya and Sindarin, and a dialect called Roquenya, spoken by the Elves of the Prairie), two dialects of Orcish (Lurkash and Southern Lurkash), three Dwarven (Khuzdul, Lake Khuzdul, and Northern Khuzdul), Goblish (Mekiitagi), Aarakocra (Windsong), and Human (Imperial, Harada, Farsski, Jemalese, Meriniri, Janoori, Mountain Speech, Ghannamic, and Talethian). The reptile folk have two languages, Skarr'taghh and Skarr'taahk (the former is "civilized" speech, basically a dialect of the latter but with a higher vocabulary, including things like "fork", "bureaucracy", "accounting", etc). Many people know at least two languages, their country's main language, and often at least one other. Most countries are based on race and culture, with the primary exception being the Tondene Empire, which absorbed two dozen or so countries in its expansion period. In the Empire, people typically know their racial language, plus Imperial. Many know more than that, especially if they work in jobs that involve meeting people of other races.
How immigrants integrate into society: They usually find some job, even if that job is beggar. Because the technology is basically medieval, their skill sets are likely to be pretty compatible. Farming is farming, smithing is smithing. Socially, they would have to watch their racial biases a little, although they could get away with quite a bit (although those that don't like Orcs can possibly have issues, since Orcs tend to have bad tempers and are physically imposing).
If the immigrant settled into a small farming town, of which there are several scattered about the landscape surrounding the larger cities, then they would likely just become farmers, like 90% of the other townsfolk. They may need to get used to the idea that the farms are typically not small family farms, but larger plantation-like farms that are run more like businesses, employing dozens or even hundreds of farmhands. They may also need to get used to the fact that the Empire has not only a City Guard, but a Rural Watch as well. The Rural Watch, while acting much like the City Guard with regards to criminal activity, has as it's primary purpose of protecting the vast agricultural lands from wild animals and monsters who may decide that the crops looks tasty, or the farmhands look tasty. Each large field (or group of smaller fields) have flags and torches to signal the Rural Watch that there is danger (the rural watch employs Aarakocra to perform overwatch duties; their flight speed and keen eyes allow them to see the flags during the day and torches at night and coordinate the groundbound Rural Watchpeople to get them where they need to go). Most countries have some variation of "farm protectors", but the Empire has the most varied racial mix, which allows them to really take advantage of racial advantages.
If the immigrant settled in a larger town or city, they would have to get used to the racial mix. Cities are cosmopolitan, and while they may have a specific race in the majority, it won't be by much. The Empire has been around for almost 900 years, and there has been a lot of mixing. Also, there is some technology that a newcomer may not be aware of: many places have indoor plumbing, pioneered in the Dwaven Undercities. "Dwarfpipes" are used in the more affluent areas. Sometimes Elven "grown buildings" may be used as well.
Another thing that might take getting used to is the Elven time sense, or lack thereof. Elves live for thousands of years (some are older than the Empire, and lived/fought in the wars of expansion), so their sense of time is rather...relaxed. They don't care what time it is, except in the most basic way. They have all the time in the world, and are rarely in any kind of hurry. They view other races as "ephemeral", and are often surprised when they go to visit a non-Elf friend that the person died of old age a decade ago. The city Elves are a bit better about this, but most Elves tend to avoid cities on general principle.
How immigrants are viewed by natives: Basically, like anyone else, if they are recognized as immigrants rather than travelers. The people on the street, so to speak, don't really care. The government tries to keep track of them, but the bureaucracy isn't big enough to police the entire land, so many are able to slip through the cracks. When they are able to catch an immigrant, they process them without too much hardship to the individual(s) involved. As crimes go, immigration is rather minor.