Jane Austen was born in 1775 and spent most of her life in the closed circle of her family. She never married (apparently an early suitor died in the midst of their courtship), but she was close to her siblings, several of whom also wrote. She began writing when still quite young; her first productions date from when she was around 12, and her first important novel, Pride and Prejudice, was begun when she was only 22. None of the works appeared in print until 1811, however, when Sense and Sensibility appeared. Her books were well-received; even royalty were fans. Austen was modest about her work, referring to it (as Virginia Woolf famously quotes) as "little bit[s] (two inches wide) of ivory on which I work with so fine a brush." She died at forty-two, having lived a quiet life.
Austen occupies a curious position between the eighteenth and nineteenth centuries. Her favorite writer, whom she often quotes in her novels, was Dr. Johnson, the great exemplar of eighteenth-century classicism and reason, and her plots, which often feature a character moving through the social hierarchy, have something in common with eighteenth-century productions like Pamela. However, her novels display an ambiguity about emotion and an appreciation for intelligence and natural beauty that aligns them with Romanticism. In their awareness of the conditions of modernity and city life and the consequences for family structure and individual character, they also prefigure much Victorian literature, particularly in this novel with its melancholy characters, scandal-filled newspapers, and rounds of parties.
Mansfield Park was written between 1811 and 1813, although it did not appear in print until 1814. It is an even more socially-aware novel than Austen's others, focusing as it does on the slave trade and the roots of the British upper-crust's wealth in corruption and exploitation. It is probably the least romantic and most pragmatic of Austen's novels, as its abrupt and rather matter-of-fact ending shows.
Regarding Maria Bertram and Mrs. Norris in the last chapter, neither leaves England. When Austen writes that "an establishment [is] being formed for them in another country," she does not mean continental Europe. Here, "country" simply means another part of the same country (most likely somewhere in the countryside). They are still in England.