Zaidiyyah source of sunnah

Your first question was answered previously:
Regarding our hadîth literature—We have the Musnad Imam Zayd, Amâli Ahmed bin Isa, Ahkâm al-Halâl wa Harâm, Jâmi’ al-Kâfi, Sahîfa of Ali bin Musa ar-Rida, and others just to name a few. Not to mention that many of our imams authored books of hadîths that they heard from their blessed ancestors! Many of the hadîths can be corroborated with the hadîthcollections of the Generality.

Keeping beard is sunnah and covering ankles is not prohibited.