The whole portion of Taittiriya Samhita 184.108.40.206 is related to Soma Sacrifice and describing the rules of it in order to complete the sacrifice ritual only, according to procedure, so that the Yajamana and his wife may get the full benefits of the soma Yajna. As the success of these elaborate rituals largely depend upon accuracy of procedure.
Let us see ...
Yes, he did.
Among the Madhyadina and Kanva Vajasaneyi Shakhas of Shukla Yajurveda, Sayanacharya has a commentary on the Kanva Samhita.
A book comprised of that commentary can be purchased from here. From the foreword/preface to Volume 1:
We have contemplated to bring out the edition of Kanva Samhita, with Padapatha and three commentaries in four ...
No, it's not present in Kṛṣṇa Yajurveda.
I've searched in Sanskrit Wikisource which contains Saṃskṛta text of Taittiriya, Maitrāyaṅī and kāthaka saṃhitās of Kṛṣṇa Yajurveda but this verse is not found in it.
There are two forms of Yajurveda: Krishna (Black) and the Shukla (White).
The Krishna Yajurveda consists of prose mixed with the mantras, therefore the word Krishna.
Among different recension of the Krishna Yajurveda, Taittrīya is the most popular one, however, Maitrāyaṇīya recension is also studied well by the scholars.
The Taittrīya Samhita has no ...
Are both Śukla and Kṛṣṇa Yajurveda saṃhitas derived from the same parent source or are they totally independent from each other?
They are totally independent of each other, but like all Vedas, there are some mantras common between both.
The Taittiriya Shakkha of the Krishna Yajur Veda was disseminated by Yajnavalkya:
Texts 64-65: Yājñavalkya, the son ...
If you are looking for a free online translation/summary of the Taittirīya Āraṇyaka, there's Essence of Taittiriya Aranyaka from kamakoti.org.
If you want to purchase in print format, you can try SAKSHI Trust's translations:
Taittirīya Āraṇyaka - Volume 1 (Srikant Jamadagni)
Taittirīya Āraṇyaka - Volume 2 (Srikant Jamadagni)
Taittirīya Brāhmaṇa - Volume 1 (...