What is the ruling on the intention of fasting, where is its place, and when is its time?
The intention is a pillar of acts of worship; it is essential, and worship is not valid without it.
Its place is in the heart, and verbalizing it is recommended so that the tongue reminds the heart. Its meaning is to be determined to abstain from nullifiers of fasting during the upcoming day with the intention of worship and obedience to Allah Almighty. This meaning is naturally present in every Muslim on every night of Ramadan, so there is no need for obsessive doubts. If one says, "I intend to fast tomorrow for the sake of Allah," it removes any doubts.
Its time is from after sunset until before the true dawn.
Is a person who forgot to make up missed fasts until the next Ramadan began required to pay expiatory compensation (Fidyah) alongside the makeup fast (Qada')?
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah.
Whoever forgets to make up missed fasts of Ramadan (Qada') until the following Ramadan begins incurs no sin, pursuant to the statement of the Messenger of Allah (peace and blessings be upon him): "Indeed, Allah has pardoned for my nation their mistakes, their forgetfulness, and that which they are coerced into doing." [Narrated by Ibn Majah, and Al-Bayhaqi in Al-Sunan Al-Kubra]
Furthermore, such an individual is not obligated to pay a expiatory compensation (Fidyah). It is stated in Bushra Al-Karim (p. 580)—one of the authoritative Shafi'i jurisprudential texts: "As for delaying it [the makeup fasts] due to a valid excuse—such as travel, breastfeeding, forgetfulness, or ignorance of the prohibition of delay (even for one living among scholars)—no Fidyah is required. This is because delaying performance during the actual month is permissible due to these excuses; hence, delaying makeup fasts is even more permissible, even if it continues for years."
And Allah Almighty knows best.
What is the ruling on eating or drinking during the second Adhan?
It is not permissible to eat or drink during the second Adhan because it announces the break of dawn and the obligation to start fasting. Allah Almighty says {what means}:"and eat and drink until you can discern the white streak of dawn against the blackness of night." [Al-Baqarah/187].
Whoever eats or drinks during this time invalidates their fast, and they must refrain from eating for the rest of the day and make up for the missed fast later.
How should I deal with the whispers of the devil with regard to ablution and purity?
Whispers in ablution are from the devil, and so you should take refuge in Allah from the devil`s evil suggestions that aim to distort the religion. Thus, once an organ is completely pure, don`t question its purity since having whispers doesn`t mean that the purity is invalid as it has already been established.