There are restrictions on details of living people so there's no way to find details of the population of the area now, but at the time of the 1901 census the townland is listed as 'Lowtown Kilcashel', and at that time there were 12 households, including 4 households that included Dolans. Total population of the townland at the time of the 1901 census was 85.
The townland of 'Lowtown Kilcashel' is closer to Ballinasloe, Co. Galway than Athlone Westmeath/Roscommon, Ballinasloe appears to be the closest town.
Moore is the name of the civil parish, and also the name of the corresponding Catholic Parish (Many Catholic parishes include parts of a number of civil parishes).
Moore civil parish is in Co. Roscommon and is contains 45 townlands, including 'Lowtown Kilcashel', which consists of just over 939 acres. The civil parish also includes two townlands named Moore South and Moore North - many civil parishes have townlands of the same name as the parish, it's often where the original Established Church (i.e. Church of Ireland) was located. Moore civil parish also contains townlands of 'Oldtown Kilcashel', 'Kilcashel Dolanstown' aka 'Dolanstown Kilcashel', the parish had no towns but did include two villages - Ballydangan in the townland of the same name, and 'Old Town' in Cloonfad townland.
With regard to the Registration Districts - The registration district for the records I mentioned above is Ballinasloe, and this district covered parts of counties Roscommon and County Galway, Creagh Sub-District is part of this overall district and it covers parts of Co. Roscommon only.
There's currently St. Mary's Church Moore, at or close to the location of the original Chapel near Moore townlands.
If you wish to learn about the various Land Divisions in Ireland have a look at the page on Irish Land Divisions at Claire Samtry's Irish Genealogy Toolkit website.
a very basic outline of the important land divisions is as follows (from largest to smallest) :
Province (4)
County (32)
Barony (~330)
Civil Parish (~2500)
Townland (~64,000)
(the numbers for some of the elements are approximate - as there are overlaps, e.g. civil parishes extending over parts of more than one county, townlands extending over more than one civil parish or barony - or both etc.)
Towns and villages are within townlands, often towns are in a townland of the same name.
In addition the the basic divisions are the ecclesistaical Diocese and parishes - Catholic and Church of Ireland (the Church of Ireland parishes often correspond with the civil parish of the same name), the Registration Districts/Poor Law Unions and Sub-Districts, and also Electoral Districts (Deds).