MCAS is qualified in many sources as fundamentally a stall prevention system.
All of those sources would be media, seeking to explain the system to the layman as simply as possible. For the media, trying to explain in terms of pitch-down moments would be way too technical. You won't hear Boeing, the FAA, or anybody on the inside describing MCAS as being for stall prevention.
From this statement, it's pretty clear that the intention was to pull the nose down hence the wording, "5 degrees of nose-down movement".
No. A system that pulls the nose down would be for stall prevention/recovery. If certification standards required that on the MAX, then Boeing would have simply added a stick pusher. The stick pusher is a vastly more simple and reliable system and has been in use on airliners for many decades now. Why would Boeing have adopted the new and unproven MCAS when they could have simply used a stick pusher?
Check how MCAS is described by insider sources. Here is one such source:
737 MAX - MCAS
Since MCAS changes the position of the horizontal stab it is absolutely effecting the pitch attitude of the plane. Or if you rather, it is effecting the pitch down forces on the plane.
When you say "effecting", I think you mean "affecting". That first sentence is false. The second is true. For the first, if you had said, "influencing the pitch attitude", then it would have been true.