What are Sensuality, Strings of Sensuality, and Fermentation of Sensuality? Can someone explain sensuality, strings of sensuality, and fermentation of sensuality thoroughly?
I want to know,

What is it?
The main cause for it.
The result of it.
Where it lies in the dependent origination?
Difference between above terms.

It'd be very helpful if you provide Sutta references with the answer.
Sensuality and strings of sensuality is a very specific translation by Ven. Thanissaro.
Piya Tan translates them in Nibbedhika (Pariyāya) Sutta (quoted below) as sensual desires (instead of sensuality) and cords of sensual pleasures (instead of strings of sensuality).

Sensual desires (kāmā), bhikshus, should be known;
The source for the arising of sensual desires should be known.
The diversity of sensual desires should be known.
The result of sensual desires should be known.
The cessation of sensual desires should be known.
The way to the cessation of sensual desires should be known.
—so it is said, but in what connection is this said?


There are these 5 cords of sensual pleasures (kāma,guṇa):
forms cognizable by the eye,
desirable, attractive, pleasant, endearing, associated with sensual desires, delightful;
sounds cognizable by the ear,
desirable, attractive, pleasant, endearing, associated with sensual desires, delightful;
smells cognizable by the nose,
desirable, attractive, pleasant, endearing, associated with sensual desires, delightful;
tastes cognizable by the tongue,
desirable, attractive, pleasant, endearing, associated with sensual desires, delightful;
touches cognizable by the body,
desirable, attractive, pleasant, endearing, associated with sensual desires, delightful.
Bhikshus, these are not sensual objects (kāma), but in the noble discipline, they are called 'the cords of sensual pleasures'

It's interesting that the last statement differentiates the two.
Piya Tan explains in his commentary:

Now that we have examined all the lines of the “kāma verse,” we can
better understand what its preceding prose line — one of the most
enigmatic statements in the early canon—means, when the Buddha
declares: “These are not sensual objects, but in the noble discipline,
they are called ‘the cords of sensual pleasures.”
In the suttas, sense-objects (kāmā) are called “the cords of sensual
pleasure” (kāma,guṇa) because we make them so in our minds. We “desire”
(kāmeti) them; we accumulate them: we make a “pile” and proliferation
(guṇa) of them—so that they become a “cord” (guṇa) that binds and
plays with us. When the enemy is named, it is known — we are in a
better position to defend, strengthen and free ourselves.

In Sabb’āsava Sutta, Piya Tan translates what Ven. Thanissaro calls &quot;fermentation of sensuality&quot; as &quot;influx of sense-desire&quot; (kām’āsava).
He explains what influxes are:

The term “influx” (āsava) refers to a category of
defilements existing at the deepest level of the mind, and which fuel
and sustain samsaric existence. The Commentaries derive
āsava (BHS āśrava, asrava) from √ŚRU, to flow. The prefix ā-can refer to
inward or outward. Hence, it can be rendered as “influxes,
influences,”since they fuel our existence and prolong our suffering.It
also refers to pus and other discharges from a bad wound; hence, it can
also be translated as “outflows, effluents,” or more poetically as
“cankers, corruptions, taints.”

Later he uses commentaries and other sources which I could not find yet, to link the influx of sensual desires to the five lower fetters of personality view (sakkāya,diṭṭhi), spiritual doubt (vicikicchā), attachment to rituals and vows (sīlabbata-parāmāsa), sensual lust (kāma,rāga) and repulsion (paṭigha).
The main cause for the cords of sensual pleasures?
From Nibbedhika (Pariyāya) Sutta:

And what, bhikshus, is the source for the arising of sensual desires
(kāmānaṁ nidāna,sambhavo)? Contact (phassa), bhikshus, is the source
for the arising of sensual desires.

What is the result of the cords of sensual pleasures?
From Nibbedhika (Pariyāya) Sutta:

And what, bhikshus, is the result of sensual desires
(kāmānaṁvipāko)? Bhikshus, one having sensual desires is reborn as
an individual into this or that existence depending on what
constitutes merit or on what constitutes demerit. — This, bhikshus, is
called the result of sensual desires.

I prefer Ven. Thanissaro's translation here for this:

&quot;And what is the result of sensuality? One who wants sensuality
produces a corresponding state of existence, on the side of merit or
demerit. This is called the result of sensuality.

Where it lies in dependent origination?
This would be my guess - cords of sensual pleasures or strings of sensuality cover feeling (vedanā), craving (taṇhā) and clinging (upādāna). So, basically between contact (phassa) and existence (bhava). These would be feeling, craving and clinging associated with sights, sounds, smell, taste and touch.