As a noun? Or a verbal noun? or both? Eg. bás d'fháil ar son an chreidimh - ar son na creideála???

Creideamh is still the noun. Creideáil the verb.

I think the vn is creidiúint, not creideamh, in WM. or maybe there is more than one take on this?

In the Knockmealdowns and Comeraghs, the north of Waterford and South Tipperary, rinn was said instead of dhein. Do rinneas.

and do rinneas is so much better than rinne mé if you're going to use rinn- - it is in fact the originally correct form, given in the tables at the back of Dinneen's dictionary.

I'd suppose before -nn, -rr, -ll -m (and some consonant clusters) where there is a long ee sound elsewhere in Munster.
So, probably: "An Rayng" for An Rinn, "aym" for im.

Yes.

Ceanntuigheoireacht, do you have a slender t or a broad t in "an t-im"?

Broad.

Anglicised Déise words not in other dialects:

Hamar (hammer)
Bruiseáil (brush)
My grandmother, while she knew all the names of every plant and flower and tree only in Gaelic, she did not seem to know the noun "bláth" for flower, rather, she said "flower" or I suppose you could say flabhar. she used bláth to mean blooming however and did not know any numbers above ten in Irish nor months. She didn't seem to have the word "pocán..." rather "billí gót" (had gabhar and all the other names like láir tho).

Out of interest: in the book An Gleann is a Raibh Ann (written in the '30s), one can semi-consistently find Irish which would probably be condemned by Father Peter. Maybe even some grammar very occasionally that PUL would mark as not 'true Irish.' The author is a native speaker in the same way I am, but Irish was not as strong there of course as it was where PUL grew up, so he uses words such as "cóip" for copy, probably not knowing the word macshamhail. My parents aren't fluent in Irish, but I was around my grandparents alot and I picked it up as early as I did English and there are words I don't know how to say in English (mainly plant names/rural terminology etc).