Regarding your second point, all incarnations should be proper nouns and therefore capitalized. It does not matter whether they are Visnutattva or jivatattva, saktyavesa-avatara or plenary expansion. The incarnations listed however may be classified as follows: Visnutattva: Kapila, Nara Narayana, Rama, Balarama, Krsna; the Purusas: the Boar, Yajna, Rsabha, Matsya, Kurma, Dhanvantari, Mohini and Kalki; Jivatattva (empowered): Narada, Vyasa, Buddha, Kumaras, Dattatreya, Prthu and Bhrgupati.
Letter to Jayadvaita, 12 July, 1970