Hi Thomas,
I am also interested in Belfast family history.
I have managed to track down my Great Grandfather through the Belfast Directories on line so I know where they lived.
1890 Belfast Street Directory
Cumming, Thomas, Bookbinder, 34 Pine St
1895 Belfast Street Directory.
Cummings, Thos., Bookbinder, 52 Portallo St
1896 Belfast Street Directory.
Cummings, Thos., Bookbinder, 52 Portallo St
1897 Belfast Street Directory.
Cummings, Thos., Bookbinder, 42 London St
1900 Belfast Street Directory.
Cumming, T., Bookbinder, 5 Titania street
1907 Belfast / Ulster Street Directory
Cumming, T., bookbinder, 5 Titania Street
So looking at the directories has been quite productive I expect that they would not be as good for some one with a common name but there is only one Thomas Cumming listed and I know he was a bookbinder.
I have found that finding information about my Belfast Family has been harder than others I am looking for.
When I find a good source of information I have added a post to this site with the link in it.
Ed