The word “devotion” cannot be applied to anything besides ‘Krishna ‘. Krishna is the only subject of devotion. Brahman is the object of knowledge, Paramatma is the object of nearness, but Krishna is the only object of service.
Sri Jiva Goswami specifically explained that Srimad Bhagavatam is the original commentary of Vedantasutra.
Unless one studies Srimad Bhagavatam under the guidance of a bonafide Vaishnava Acharya, he will not be able to understand the real purport of the Brahma-sutra. Srimad Bhagavatam is the original commentary of Vedanta-sutra.
The deity is the merciful incarnation of the eternal form of the transcendental Supreme Personality of Godhead of the spiritual sky (Vaikuntha). It is direct proof of the personal form of the Supreme Personality of Godhead. Vaishnavas do not imagine whether God is a person or impersonal. They are not idol worshippers.