Commoners
The Noble Houses ruling the Empire represent only a tiny fraction of its population; the rest are known as commoners. In fact, there are a variety of social classes grouped under this banner, with some commoners even being wealthy enough to own expensive Legacy devices such as Gravcycles.
In the last fifty years the general literacy levels have increased; printed news-sheets are circulated by the Noble Houses in the larger cities, although being written by the Nobles these tend to be mostly propaganda. But as most families have access to clean water, food, electricity (through Legacy power cells) and labour-saving devices they tend not to object to their lot in life.
The exact social mix on any given planet is determined partly by the governing House and partly by its type. Those born to families of a lower station have very little chance to make much of their lives, tending to be illiterate and only able to take on similar menial jobs to their parents. The middle-class commoners tend to be more literate; these end up in skilled jobs and have the opportunity to make their own way in life. Higher classes also exist on some planets and these individuals may run large estates or portions large businesses of on behalf of their Noble masters, though it is virtually impossible for a commoner to engage in interstellar trade without a Noble sponsor due to the restrictions of the Imperial Guild of Merchants.
Whilst few commoners will ever attain Noble status, the most talented individuals are still able to distinguish themselves. Notably, psychics are often detected when their abilities begin to manifest uncontrollably at the age of around 11. These psychics are then quickly ushered into the Noble House which governs their planet and sent to the Psi School to be trained. It is also possible for those working for the Technologists or Chirurgeons as mere technicians to be recognised as having potential for greatness and thus be elevated to the Nobility and allowed to conduct experiments on the devices which as commoners they were only permitted to operate.
The military of the Empire is primarily made up of commoners, with Nobles only normally taking on roles as commanding officers. Indeed, commoners are never promoted to a position where they could feasibly give orders to a Noble such as a position on the bridge of a spaceship; the very thought is distasteful. It is however possible for a talented commoner to be promoted to Noble status in order to further his military career.
There are two major exceptions to these basic principles, however. In House Karpeer, everyone is put through a basic schooling program and then assessed for their aptitude for further learning. Those who fail are destined for a life of manual labour; those who succeed continue their education. This process is repeated several times, eventually leading to individuals who have graduated the Prime University and are worthy of becoming Nobles.
In House Truniss, anyone not of the Noble bloodlines is unable to attain that status later in life and anyone born to the correct families is accepted as a Noble regardless of aptitude. There are rumours of some people having their birth records 'adjusted' to ensure that they attain the appropriate status, but these are denied by the House's record-keepers.
Planets
Education levels and social makeup vary greatly between different types of planet; even in House Karpeer the inhabitants of mining worlds tend to be much less educated than elsewhere. In general though, Karpeer worlds have around 20-30% better literacy levels than equivalents on other worlds.
Mine worlds
Very little education is needed to work the mining machinery on most mine worlds. The people living in mining colonies tend to be more concerned with day-to-day survival and trying to scrape out a decent living in unpleasant surroundings. Whilst they tend to be uneducated and mostly illiterate (10-20% literacy levels are the norm), they do tend to be reasonably intelligent; when every day is a risk, a certain natural ability to spot and avoid danger is needed. Very few people of higher social status live on Mine worlds due to the uncomfortable conditions.
Agri worlds
The vast majority of the land is generally taken up by farming and so is sparsely populated by farming families who tend to be uneducated and often clannish. However, in the cities which are dotted around the education level is much higher, closer to that of a mix world with a number of middle class areas. There are also often a handful of upper class families who manage much of the food production for the Nobility. Most traders on Agri worlds tend to be commoners, although very few of these can ship their products off-world; this is the domain of the Nobles.
Factory worlds
Whilst Factory worlds may have a lot of manufacturing capability, the Technologists who supervise the Autofactories are all Nobles, though they have a large number of skilled commoner assistants. Additionally, a large amount of infrastructure is needed to manage the import of raw materials and the export of finished goods. Education levels are almost as high as that of mix worlds, with large numbers of skilled administrators required to organise the huge movements of materiel that are daily routine on Factory worlds. There tend to be very few higher class commoners, with little they can offer to the Noble houses who manage the Autofactories directly.
Mix worlds
Education tends to be highest on mix worlds as they are the most civilised of all the worlds of the Empire; there are large numbers of schools, and even colleges and some universities that take commoners. There are often a number of wealthy commoners who operate these large institutions or perhaps businesses run from the world.
Death worlds
Most death worlds only have purpose-built installations filled only with skilled personnel; as a result, education levels are very high. However, on worlds where larger cities have been built the education levels are often lower than Agri worlds. As there are less facilities, literacy and general education tend to be lower. However, there is usually a high turnover of personnel, with new skilled personnel arriving all the time.