Any proof in the Chaitanya Charitamrita that Chaitanya Mahaprabhu says Mahavishnu is an incarnation of Krishna? Apologies to anyone offended by my question.
I am only answering the following question:
Any proof in the Chaitanya Charitamrita that Chaitanya Mahaprabhu says Mahavishnu is an incarnation of Krishna?
Yes, in Chaitanya Charitamrita, Madhya, Chapter 20 Chaitanya Mahaprabhu says that Lord Maha Vishnu is an incarnation of Lord Krishna.
CC Madhya 20.250
prathamei kare kṛṣṇa ‘puruṣāvatāra’
seita puruṣa haya trividha prakāra
“In the beginning, Kṛṣṇa incarnates Himself as the puruṣa-avatāras, or Viṣṇu incarnations. These are of three types.
CC Madhya 20.251
viṣṇos tu trīṇi rūpāṇi
puruṣākhyāny atho viduḥ
ekaṁ tu mahataḥ sraṣṭṛ
dvitīyaṁ tv aṇḍa-saṁsthitam
tāni jñātvā vimucyate
“ ‘Viṣṇu has three forms called puruṣas. The first, Mahā-Viṣṇu, is the creator of the total material energy [mahat], the second is Garbhodaśāyī, who is situated within each universe, and the third is Kṣīrodaśāyī, who lives in the heart of every living being. He who knows these three becomes liberated from the clutches of māyā.’
It is said in the Bhagavatam 12.13.18:
Śrīmad-Bhāgavatam is the spotless Purāṇa (amalam — perfectly pure Purana). It is most dear to the Vaiṣṇavas because it describes the pure and supreme knowledge of the paramahaṁsas (topmost devotees). This Bhāgavatam reveals the means for becoming free from all material work, together with the processes of transcendental knowledge, renunciation and devotion. Anyone who seriously tries to understand Śrīmad-Bhāgavatam, who properly hears and chants it with devotion, becomes completely liberated.
It is said that the Puranas are classified according to the influence of the three qualities of material nature to sattvic (pure) Puranas, rajasic Puranas (impure with passion), and tamasic Puranas (impure with darkness or ignorance). And in the above verse it is said that the Bhagavatam is amalam "perfectly pure" Purana, which means that it gives the best and purest Vedic knowledge to learn among all the Puranas. It is even said in some other Puranas that the Bhagavatam is the best of all the Puranas.
That is why Sri Caitanya told to his followers to learn the Bhagavatam.
Here are some quotations from the Caitanya caritamrita (a biography of Sri Caitanya) about the importance of Bhagavatam:
- CC Madhya 25.153, https://www.vedabase.com/en/cc/madhya/25/153
Śrī Caitanya Mahāprabhu advised Prakāśānanda Sarasvatī, “Study Śrīmad-Bhāgavatam very scrutinizingly. Then you will understand the actual meaning of the Brahma-sūtra.”
- CC Antya 13.113, https://www.vedabase.com/en/cc/antya/13/113
Śrī Caitanya Mahāprabhu said to Raghunātha Bhaṭṭa, “When you return home, serve your aged father and mother, who are devotees, and try to study Śrīmad-Bhāgavatam from a pure Vaiṣṇava who has realized God.”
- CC Madhya 19.115, https://www.vedabase.com/en/cc/madhya/19/115
Śrī Caitanya Mahāprabhu taught Śrīla Rūpa Gosvāmī the ultimate limit of the truth about Lord Kṛṣṇa, the truth about devotional service and the truth about transcendental mellows, culminating in conjugal love between Rādhā and Kṛṣṇa. Finally He told Rūpa Gosvāmī about the ultimate conclusions of Śrīmad-Bhāgavatam.
The followers of Sri Caitanya also used to study or recite the Bhagavatam together with the learned men of the society:
- CC Madhya 19.17, https://www.vedabase.com/en/cc/madhya/19/17
Śrī Sanātana Gosvāmī used to discuss Śrīmad-Bhāgavatam in an assembly of twenty or thirty learned brāhmaṇa scholars.
- CC Ādi 10.158, https://www.vedabase.com/en/cc/adi/10/158
While he (Raghunātha Bhaṭṭa Gosvāmī) stayed with Śrīla Rūpa Gosvāmī, his engagement was to recite Śrīmad-Bhāgavatam for him to hear. As a result of this Bhāgavatam recitation, he attained perfectional love of Kṛṣṇa, by which he remained always maddened.
I suggest you read the purports to those verses at the above links.