2b] Is there a Sunnah prayer before Jumua‘ah?

there was only this adhaan immediately before the khutbah, and that is
the Maaliki madhhab until the present day.
If you were to say: perhaps he (blessings and peace of Allah be upon
him) offered the Sunnah prayer in his house after the sun passed the
zenith,then he came out? I would say: If he did that, his wives (may
Allah be pleased with them) wouldhave narrated it from himas they
narrated all other prayer s that he did in his house by night and by
day, and the way in whichhe prayed tahajjud and qiyaam al-layl. As no
such thing as been narrated, the basic principle is that it did not
happen and thatit was not prescribed. End quote.
This issue was discussed further and at length by Imam al-Haafiz Abu
Shaamah (may Allah have mercy on him). See: al-Baa'ith 'ala Inkaar
al-Bida' wa'l-Hawaadith, p. 96 ff.
To sum up: There is no regular Sunnah prayer prescribed before
Jumu'ah; rather what is prescribed is to offer whatever voluntary
prayers one wants, from the time one enters the mosque until the imam
ascends the minbar.
And Allah knows best.
:-* key word:- Voluntary Prayers