To answer your first question, sf = sfz in Dorico. To eliminate the suffix sub. from immediate dynamics, select them and execute the command Edit>Reset Appearance.
Thanks John that worked to deactivate subito . Good to know that sf and sfz are the same. This enables me to use the same designation as in the original score. Further reflecting sfp in the Beethoven scores might actually be subito forte piano.
At the risk of being pedantic, I point out that the s in sf does not stand for subito nor would Beethoven, who knew Italian, have understood it that way. The Italian verb sforzare is one of a group of words that begin in sf, including sfortuna (misfortune), sfinito (exhausted). The s- is a prefix (I assume descended from an earlier form des-) that acts as an intensifier, so that forzare (to force) becomes sforzare which means ‘to force’ but also ‘to strain.’
The sfp that Beethoven uses is an abbreviation of sforzato-piano.
Beethoven, the composer most associated with subito dynamics, used sf and nothing but sf (no fz or sfz) as a strong accent throughout the first editions and manuscripts of all of his 32 piano sonatas. He never used sf to mean subito forte nor, to my knowledge, did the major composers who followed him.
And I agree with Mark Johnson above about pf. It is such a rare marking that it doesn’t even deserve to be in a list of standard dynamics, much less in first place.