“Your second question about falling down from the brahma-jyoti is answered that it is not that one must fall down, but that they generally fall down. There is a verse in the Srimad-Bhagavatam, (10.2.26) which says, “My dear lotus eyed Personality of Godhead, persons who are very proud of becoming one with the Brahman effulgence and thereby consider that they have become liberated are factually in a contaminated consciousness on account of the absence of devotional service unto You. Such persons may rise to a high level of spiritual understanding as far as the impersonal brahmajyoti but on account of the lack of devotional service unto You, they generally fall down again into material contamination.”
(SPL to Harer Nama, 21st December, 1968)
Regarding your questions: The spark soul has certainly form which means hands, feet, etc. This we learn from Bhagavad-gita. The body is described there as vasamsi, which means dress. So unless one has got originally hands and legs, how the dress, coat and pants and shirt, takes such form? Therefore, the spirit soul has original form. When he is in the material energy the dress is evolved materially and when he is in the spiritual energy the dress is evolved spiritually. This is also not very difficult to understand, as our students before coming to my contact, he was supposed to be materially dressed, attached to sense gratification, and after devoting himself in Krsna consciousness, he is gradually developing a spiritual dress. That means attached to satisfying the sense of the Supreme.”
(SPL to Rupanuga, 14th March, 1969)