Answer:
There is no specific volume that a player must be at when playing at a forte level, or a mezzo forte. It's up to the creative interpretation; it's up to the conductor and the musicians.
A piano is not always the same. If you're playing a violin concerto, your piano might be a soft but carrying whisper, as opposed to if you're playing an ostinato in a wind band (ugh, alto saxophone parts). This is part of what makes music so extraordinary. There are surely right and wrong ways to do things; an Eb will never be an E, but how you play, your expression, is entirely up to you.
You can always count. Remember the sharps start with C since there are no alterations. The count a fifth and you arrive at G etcetera. With the flats count fourths.
That is because time symbolizes chaos. It is similar to what is seen in the poem Ozymandias. Time is not something that can be controlled or something that we can beat. It's passage is inevitable and we can only let it take over.
