Thanks for these comments, much appreciated. In regard to the "deeper level of exchange" there is also the aspect that rasabhasa may occur if one gains impressions of different types of rasa from previous lifetimes- and it is described that these impressions come from an advanced devotee who has the taste for that rasa. So, discussing sakhya lila with some advanced vaisnavas might be counterproductive if one were aspiring for madhurya, vatsalya or dasya. In that sense it would seem that one should seek out association of advanced devotees whose rasa we aspire for- while at the same time offering due respects to all advanced devotees.
Yes, this is all confirmed in the NoD:
Srila Prabhupada: "The word rasa, used in the Bhakti-rasāmṛta-sindhu, is understood by different persons differently because the exact English equivalent is very difficult to find. But as we have seen our spiritual master translate this word rasa into "mellow," we shall follow in his footsteps and also translate the word in that way.
The particular loving mood or attitude relished in the exchange of love with the Supreme Personality of Godhead is called rasa, or mellow. The different types of rasa, when combined together, help one to taste the mellow of devotional service in the highest degree of transcendental ecstasy. Such a position, although entirely transcendental to our experience, will be explained in this section as far as possible, following in the footsteps of Śrīla Rūpa Gosvāmī."
Yes, in one's previous life or in this life this taste for bhakti-rasa has come about:
"This relishing of transcendental mellow in discharging devotional service cannot be experienced by all classes of men because this sweet loving mood is developed only from one's previous life's activities, or by the association of unalloyed devotees. As explained above, association with pure devotees is the beginning of faith in devotional service. Only by developing such faith in the association of a pure devotee, or by having in one's previous life executed devotional activities, can one actually relish the mellow of devotional service. In other words, this transcendental bliss is not to be enjoyed by any common man unless he is so extraordinarily fortunate as to be in association with devotees or to be continuing his previous birth's devotional activities.
The goal, the attainment and the siddhi, the perfection of all our activities:
"tan-nama-rupa-caritadi-sukirtananu-
smrtyoh kramena rasana-manasi niyojya
tisthan vraje tad-anuragi-jaganugami
kalam nayed akhilam ity upadesa-saram (Nectar of Instruction, v.8)
"The essence of all advice is that one should utilize one's full time-twenty-four hours a day-in nicely chanting and remembering the Lord's divine name, transcendental form, qualities and eternal pastimes, thereby gradually engaging one's tongue and mind. In this way one should reside in Vraja [Goloka Vrindavana-dhama] and serve Krishna under the guidance of devotees. One should follow in the footsteps of the Lord's beloved devotees, who are deeply attached to His devotional service."
In the purport to this verse Srila Prabhupada explains further:
"When one makes Vṛndāvana his residence, he should take shelter of an advanced devotee there. In this way one should always think of Kṛṣṇa and His pastimes. This is further elucidated by Śrīla Rūpa Gosvāmī in his Bhakti-rasāmṛta-sindhu (1.2.294):
kṛṣṇaḿ smaran janaḿ cāsya
preṣṭhaḿ nija-samīhitam
tat-tat-kathā-rataś cāsau
kuryād vāsaḿ vraje sadā
"A devotee should always reside in the transcendental realm of Vraja and always engage in kṛṣṇaḿ smaran janaḿ cāsya preṣṭham, the remembrance of Śrī Kṛṣṇa and His beloved associates. By following in the footsteps of such associates and by entering under their eternal guidance, one can acquire an intense desire to serve the Supreme Personality of Godhead."
Again Śrīla Rūpa Gosvāmī states in Bhakti-rasāmṛta-sindhu (1.2.295):
sevā sādhaka-rūpeṇa
siddha-rūpeṇa cātra hi
tad-bhāva-lipsunā kāryā
vraja-lokānusārataḥ
"In the transcendental realm of Vraja [Vraja-dhāma] one should serve the Supreme Lord, Śrī Kṛṣṇa, with a feeling similar to that of His associates, and one should place himself under the direct guidance of a particular associate of Kṛṣṇa and should follow in his footsteps. This method is applicable both in the stage of sādhana [spiritual practices executed while in the stage of bondage] and in the stage of sādhya [God realization], when one is a siddha-puruṣa, or a spiritually perfect soul."
Yes, we are praying for this heart and soul, the association of advanced devotees whose rasa we aspire for:
The effect of contact with an advanced devotee is described by Srila Bhaktivinoda Thakura in Harinama-cintamani:
"If one stays near a pure Vaishnava [devotee of Krishna] for some time, one can receive the bhakti [devotional energy] flowing from his body. If one can bind that energy within one’s heart, after one develops strong faith bhakti will develop…. Thus if one lives close to a Vaisnava, devotion will soon appear within one’s heart."