It is 500BCE and I am a resident of Pasargardae, in the Achaemenid Persian Empire, the largest empire the world has known. What is my life like?

Thanks to u/OldPersonName for bringing this thread to my attention. I've been a bit busy lately, but here's some thoughts about this questions specifically.

Pasargadae in 500 BCE is a particularly weird example to work with. Regardless of what Cyrus the Great may have intended when he started building a palace there, Pasargadae never developed into a city, or even a hub of local administration. While Darius I the Great completed the projects that were already underway at Pasargadae, he chose Persepolis as his own palace site in Parsa (the Persian home province), and given its proximity to Pasargadae, the new location became the center of government and interest in the region by about 510 BCE.

Pasargadae on the other hand became a ceremonial center and a royal retreat. The princes and royal women of the Achaemenid court were not bound to follow the king at all times, and often had access to the royal estates that were not being used by the main court. So occasionally some of the other royals may have set themselves up in Pasargadae's palaces for a few months out of the year, but it's primary purpose in the historical record was as the site of Achaemenid coronation ceremonies, the necropolis for Cyrus' family, and religious activities. As such, the most visible occupants most of the time would have been the priests who conducted ceremonies at the altars, sanctuaries, and tombs near the periphery of the palace complex. These priests must have had servants, bureaucrats, and other support staff working around them, but all of these roles are actually better understood through sources found at Persepolis, so I'll address them below.

What is my house made of?

This is probably the hardest question to answer. Even if we stick to the best excavated administrative centers in southern Iran, Persepolis and Susa, the answer seems to be no house at all. In the two most famous Persian capitals of all, there is not a shred of evidence for permanent structures that are not monumental palaces and administrative buildings. There are no obvious markets or residential houses. There aren't even structures we could readily identify as temples. This stands in contrast to earlier Elamite layers at Susa and other sites like Liyan.

Of course one possibility is that the right areas just have not been excavated properly or at all. The modern city of Shush surrounds the excavated parts of ancient Susa, making archaeological work nearly impossible, and the area immediately west of the palace complex at Persepolis was destroyed without excavation to make room for a park and parking lot in the 1970s. However, the area west of the park does show evidence for Achaemenid-era inhabitation in the form of ceramics and metal work, but without any evidence of permanent structures. Both sites have massive open areas like this. This has led to a working theory that the migratory nature of the royal court instigated a sort of traveling city, in which all of the support staff and common classes that would normally settle around major administrative centers also migrated. Rather than having permanent structures in any one place, they lived in sturdy, semi-permanent tents similar to yurts much like the nomadic herders in the countryside. If you were a commoner, or even a mid-level bureaucrat or priest, working near the royalty and nobility, these tents are the most plausible form of housing based on available evidence.

What occupations are open to me?

This question is easier to answer, but filled with caveats. The most valuable sources for ordinary people in the Achaemenid period are the Persepolis Fortification and Treasury Archives - two collections of thousands clay tablets from the Persepolis regional administration written in Elamite cuneiform. Individual tablets are still being translated and published all the time, but Cameron, 1948 and Hallock, 1969 are the most comprehensive collections, but bear in mind if you use those that names of people and places are usually left untranslated, so you may need to search the index or ctrl+f to find what you're looking for.

These tablets reveal thousands of workers called kurtash receiving rations from the central administration. Kurtash seems to cover a wide range of laborers doing everything from skilled crafts like carving reliefs and inlaying precious stones or metals to day laborers quarrying and carving stone for royal building projects or digging canals to more simple crafts like weaving baskets and making pottery. It also covers a wide range of backgrounds to include free peasants, prisoners of war, and probably slaves given to the royal administration as tribute from some of the outlying provinces.

Though it is never articulated in the Achaemenid period, later Iranian sources describe a system not unlike the Three Estates of late-medieval Europe, where the nobility, priesthood, laboring class, and merchant/artisan classes are all hereditary and constant. It is clear that the nobility and priesthood functioned this way in the Achaemenid period, and all historical precedent available in the surrounding regions of Elam and Mesopotamia indicate that the lower classes operated the same way. So, if you're father was a stone mason, you became a stone mason. If your father was a Greek deported to a village that harvested bitumen, then you harvested bitumen. If your father was a skilled relief carver, you get the idea.

Many of the kurtash also seem to be corvee labor from provinces across the empire. As part of their tax burden, they were required to travel to work on royal projects. This led to Egyptians, Carians, Greeks, Assyrians, Indians, and many others to take up temporary residence among the local Iranian ethnicities and work on the same projects.

Additionally, the Persepolis Archives reveal the presence of a plethora of bureaucrats and priests. Bureaucrats covers scribes, kurtash overseers, and administrators coordinating the transfer of supplies from one site to another, in an area stretching upwards of 100 miles away from Persepolis. This is the category with a degree of upward mobility. Over the 52 year span covered by these archives, it is clear that several people rose through the ranks of the imperial administration. These bureaucrats included hereditary families who all worked in the treasury, but also eunuchs, who came from other backgrounds from across the empire and were castrated as young boys before being trained as scribes and other low level office workers.

The priesthood is somewhat self explanatory, but covers a wide range of deities including those of conventionally Zoroastrian origins, otherwise unknown Iranian cults, and the well established Elamite pantheon that was native to the region. Several priestly titles appear, but none seem to have any obvious prominence over the others. These priests served communities from the heights of the royal necropoles at Naqsh-e Rostam and Pasargadae down to unidentifiable farming communities.

What do I wear?

This is difficult to answer in any ancient context because textiles simply do not last for very long. One safe bet, based on thousands of years of artistic evidence, is that the lowest rungs of society almost always wore simple tunics made from whatever textiles were locally available. In Parsa that was probably linen or wool depending on the season. In the Achaemenid period particularly, the other conventional option seems to have been the traditional Iranian riding costume. A short tunic, tight fitting trousers, leather turn-shoes or boots, and a felt cap. This basic outfit seems to have reached across classes to a certain degree, with the colors of available dyes and additional jewelry ornamentation becoming the more important class signifiers. Some examples of clothing worn by ordinary people in ancient southern Iran can be seen in the so-called salt mine mummies.