From MN 49 (trans. Sujato):
Consciousness that is invisible, infinite, radiant all round—that’s what is not within the scope of experience based on earth, water, fire, air, creatures, gods, the Creator, Brahmā, the gods of streaming radiance, the gods replete with glory, the gods of abundant fruit, the Overlord, and the all.
Viññāṇaṃ anidassanaṃ anantaṃ sabbato pabhaṃ ...
The invisible consciousness (viññāṇaṃ anidassanaṃ) from MN 49 seems to be different from the sense consciousness described in MN 18 e.g. eye-consciousness, ear-consciousness etc. because it is not within the scope of sense experience, according to MN 49. It is also found in DN 11. It is also translated as "consciousness without surface" (from here, trans. Thanissaro).
Question 1: Question 1:
What is the invisible consciousness or consciousness without surface described in MN 49 and DN 11?
Is it a cosmic consciousness like the one found in Hinduism? I guess not.
Question 2: Question 2:
This answer implies that this invisible consciousness or consciousness without surface is the re-linking consciousness (patisandhi-viññana) that connects one lifetime to the next. This also implies that the re-linking consciousness (patisandhi-viññana) which is the invisible consciousness or consciousness without surface (viññāṇaṃ anidassanaṃ) is the consciousness that descends into the womb causing materiality-mentality (nāmarūpa) to arise (from DN 15). Is this right?
Question 3: Question 3:
Also, the description of "invisible, infinite and radiant all round" sounds very similar to the "luminous mind" (pabhassara citta) from AN 1.51-52. The same word "pabham" (luminosity) or "pabhassara" (luminous) is used in both MN 49 and AN 1.51-52. How is the invisible consciousness or consciousness without surface related to the luminous mind?