You haven’t said what exact denomination the Hunter family was though I would guess from the surname and the general area that they lived in that they were Presbyterian. There are several Presbyterian churches around Whiteabbey but the only one with records back to the 1700s is Carnmoney, which is a very old congregation, dating back to the arrival of the first Scots in the area in the 1600s. They have the following records:
Baptisms, 1708-60, 1767-1807 and 1819-1968;marriages, 1708-58, 1767-89 and 1819-41; notebook giving marriages, births and deaths of various families, with an index, 1708-1917; session minutes which often include minutes of session and committee, 1686-1748, 1767-1821 and 1847-1933; names of those who transferred from other congregations, 1708-25 and 1859-60; poor lists, 1716-84 and 1878-80; accounts, 1895-98; registers of seat holders and pew rents,1908-16, which contain plans of the meeting house,1862-3, deaths of ministers, elders and members of committee, 1861-1916, extracts from wills recording bequests to the church, 1714-1909, lists of ministers and elders and when ordained, 1657-1908, and a list of 1st World War volunteers from the congregation, 1918; treasures account books, 1913-25;
Tradition was to marry in the bride’s church after which she would attend her husband’s, so marriage and children’s baptisms are not always found in the same churches records. You say that Ellen Rea was married in Magheramorne. Rea again suggests a Presbyterian background. There is a Presbyterian church in Magheramorne but it only has records from the 1880s. I am not sure if it was open in 1822. Otherwise the bride may have married in Larne which is close by. Larne has several Presbyterian churches. Though there are records back to the 1720s for Larne Non Subscribing church, none of the churches there has any marriage records for around 1822.
The Carnmoney Presbyterian records don’t appear to be on-line anywhere and so you would need to get a researcher to look them up for you in PRONI (the public record office) in Belfast. If you don’t find them in Presbyterian records, you could try the Church of Ireland (ie Episcopalian).
Researchers in the PRONI area: http://sgni.net
In terms of finding out more about the couples lives there probably aren’t many records that are likely to list them, apart from church records. The area where they lived (Magheramorne and Whiteabbey) was then all agricultural land. So the majority of the population were farmers or farm labourers/weavers, plus the odd skilled person such as a carpenter or stonemason. Magheramorne remains agricultural land. People still farm there today but many residents commute into Belfast or Larne. Whiteabbey today is mostly housing estates on the edge of Belfast, with some light industry. Farming provided a reasonable living in the 1800s (the land in Co. Antrim is very fertile) but a farm was normally left to the eldest son, meaning younger sons had to leave and make their own way in the world. Labouring was much less profitable, though a little extra income came from weaving in the winter months, but it wasn’t a wealthy life. The industrial revolution largely passed Ireland by because it has few natural resources, and so there weren’t the new jobs here that were to be found in Scotland, England, America, Canada, Australia and elsewhere. And for those with a little cash who wanted their own farm, land was in short supply, and rarely available for outright purchase, whereas it was possible to acquire or buy land in the countries mentioned. There had also been a population explosion with the population of Ireland going up from 3 million in 1741 to 8 million in 1841. There just weren’t jobs for all those people. These could all have been factors in the couples decision to emigrate.
On the other hand, if John Hunter was a carpenter, there would have been work for him in Belfast where the city was expanding, and new houses were being built, and where some shipbuilding was taking place. Who knows?
Unless your passage was paid by a grant or a sponsor, or you were transported, Australia was more expensive to get to, and so I have heard it suggested that emigrants there sometimes had a little more spare cash than those who headed for places closer to home.