The way to find employees is the account books of the estate. Not too many of these on line but
could be located in a local library under 'local studies' or in the National Library in Dublin.
A bit of information about estates can be found at www.landedestates.ie
you could look there.
National Library, Dublin has Prior-Wandesford Estate and family papers. Collection lists 52 & 101
The Wandersforde family also had lands in England as well. Most of the land in Ireland was given to the Nobility as gifts for favours done.
Often families were just tenants/farmers on estates, paying rent to perhaps a head tenant who was renting from whoever owned the Estate. They could be employed to work on the estate as well as perhaps a carpenter or within the house but mostly were farmers and renting especially at the dates you list above.
Griffith Valuation took place in Kilkenny in 1849. www.askaboutireland.ie
The Parish of Castlecomer was in the Poor Law Union of Kilkenny (within 12 mi)
There are 8 Flewellin's: These rent from a common landlord the Hon. C.B.Wandesforde
James,& John in Townlands Coolbaun and Thomas & Martha of townland Gorteen
James Flewellin, tenant of George Leacock,
#10a house, outbuilding and land 24 acres 3 roods and 30 perches
John Flewellin, tenant George Leacock
#16c house and garden 0 acres 0 roods and 15 perches (1 perch 18'x18') (obviously not farming)
Thomas Flewellin , townland Gorteen, tenant of George Leacock
18a house and land 0.3.14 and rents a house on the property to Anne Mathews 18b (no land)
#20 Thomas Flewellin, land 2.3.22 (you often see a farmer renting extra land)
Anne Taylor, townland of Gorteen, tenant of CBVanderforde
#16 house and land 3.0.15 (don't see a Robert in Gorteen)
Robert Taylor, Parish Castlecomer, Townland Coolbaun
#22 house and land 8.3.16
other Taylors Coolbaun: 1 Joseph Taylor, 4 Alexander Taylor, 5 Henry Taylor could be brothers?
There are no Flewellins in the current Kilkenny telephone book and 4 Taylors, 8 Williams.
All have addresses sufficient for mail delivery.
There were no Flewellins in either the 1901 or 1911 Census: www.census,nationalarchives.ie
This maybe a matter of spelling, or a lot of females who married and then disappear.
Martha Flewellin, townland Gorteen, tenant of CBVanderford
#45 house, outbuildings and land 49.1.38
Rare to see property in women's names, she is probably a widow and asked permission to have the lease transferred to her own name.
A note that the townland of Gorteen has 'collieries' which would mean mining - usually coal but
being Ireland could be copper? I went to the 1837 Lewis Topographical Dictionary which shows
Castlecomer had an extensive coal field, there was also iron. This would be a source of employment other than farming.
The C.B. stands for Charles Butler Wandesford
George Leacock mentioned above as a landlord had himself 2 landlords, one of course
being C.B.Wandesford and a Joseph Renor.
In 1858 a Henry Flewellin had a Will, the executor was C. Flewellen of Killalane. Transcript
National Archives IWR/1838/F/533 Vol. 4/237/3
I believe if you contact the National Archives they may be able to help you, usually you have to go in yourself but some people are having success with requests on line.