Here is an exact picture of what i'm working with; my "clean wall hole". Note there is a little bit of plaster/whatever that chipped out all the way to the metal mesh back. my goal was to fill this in all the way so there isnt breakage or pieces moving around in years to come.
RE: It being the wrong one" - This was actually the ONLY ceramic toilet paper holder I found after searching about 5-6 places here in Atlanta. I found this one at a specialty floor/tile place, and it was the ONLY one they had.
Bud, I will try to research your suggestion in regards to modified thinset.
If there are any additional suggestions, I'm open. and always, Thanks a ton for your help!
How many parts, water to mortar do you recommend to "mix it fairly dry" vs the average mix you would do?
I have no idea. I would just start off mixing until it gets pasty. Thinset will run and sag fairly easily so you'll just have to play around with it a little. Sorry I don't have a better answer for you on that score. I always mix thinset by sight and by feel.