The word “ahora” (or the diminutive “ahorita”) can mean “now”, “just now” or “shortly/right away”. So, it can have a present, past or future meaning.

For example:

Ahora trabajo en el banco. (I work in the bank now.) [present]
¡Justo ahora lo ví! (I saw him just now!) [past]
Ahorita te llamo. (I’ll call you right away.) [future]

As for the phrase “en este momento”, we tend to translate it as “right now”.

For example:

En este momento estoy ocupado. (Right now I’m busy)

But, when we change this to “en ese momento”, we translate it as “then” or “at that time”.

For example:

En ese momento, tenía problemas de salud. (At that time, I had health problems. / I had health problems then.)

As for the word “ya”, there are many, many uses. In general, we can think about it as “now”, “already”, in negative statements “any longer”. We can always associate a sense of imminence with the word “ya”.

For example:

Ya hablé con él. (I already spoke with him.)
¡Hágamoslo ya! (Let’s do it now!)
Martín ya no vive en Madrid. (Martín doesn’t live in Madrid any longer.)

Here are some more idiomatic cases:

¡Ya nos vemos! (See ya’ soon!)
¡Ya! (Enough already!)
¡Ya pues…! (Come on…!)

Does this help? Have you heard it used in other ways that aren’t mentioned here?

Tabloids!!! You said it, Alan! Any know anything available online to give us an example of “la prensa amarilla”…? My sense is that Alan’s right, that these tabloids are sponsored by interest groups, but… what are their interests? What are they promoting?