Yes, it is very good to perform the missed prayer of your deceased prayers. It will help him and you will also get great reward iA.

Wassalam.

Buying and selling currencies is permissible as far as you do not harm the general public..

Wassalam.

Allah (SWT) saved and saves billions of human beings from harm with out forcing them, but He has given us free will and ability and help to do good or the freedom to do bad if we opt for it . Many prophets and infallible Imams were killed by enemies of Allah who opted to be criminals and insisted on that. Allah (SWT) does not force people to avoid bad as He has examined them and gave them free will after showing them the right path.

The crimes are the responsibility of the criminals and we can never expect Allah (SWT) to stop the criminals, otherwise the whole system of life will be disturbed as life is based on free will to do good or bad and there no meaning of good or bad if we expect Allah (SWT) to force people.

Wassalam.

Just having an attraction toward something can never justify doing it when it contradicts with the discipline set by The Creator who distinguishes between good attraction and bad attraction. Many persons have sexual attraction towards incest or children or married women and men etc. It must be clear that just feeling the sexual attraction does not legitimize what you are attracted to. Many people are attracted to drugs and billions of dollars are spent in today's world on drugs, but can such attraction legitimize the drugs? Desire is the originator of attraction and it can be be pure desire which initiates attraction towards good things, and can be bad desire which initiates bad attractions.

Allah (SWT) who created us and every thing and knows about every thing has told us to avoid impure desires and never go after evil attractions. In fact it is one of the best forms of piousness is to go against the impure desires (And as for him who feared standing in front of his Lord (Allah), and restrained himself from impure desires, then the Paradise will be his abode. (Sura 79, Verse 40 and 41).

Allah (SWT) did not forbid any act but only because it is harmful )ويحرم عليهم الخبائث (Sura 7, Verse 157)

Allah (SWT) mentioned in Quran (And remember (prophet) Lut, We granted him prophet hood and knowledge and we saved him from the people who used to do evil acts. (21:74) ونجيناه من لقرية التي كانت تعمل الخبائث

Every evil act is forbidden whether some people are attracted to it or no. Millions are attracted to alcohol, drugs, pork, and fornication etc but it remain evil acts in the reality, so it remains forbidden (Haraam). Forbidding evil acts and impure desires is essential to  save life and human beings.

Wassalam.

Islamic rules forbidding seeing or touching other gender (Non Mahram) are very clear but exceptions come if there is a real necessity to save life. Necessity must be assessed and the exception should meet no more than the necessity. Any act more than the real necessity is not permissible.

Wassalam.

Yes they are allowed to hold hands in public provided that:

1. her hands above the wrists should not be shown to outsider men .

2. Holding hands in public should not encourage sinful acts or sinful habits.

3. Holding hands in public should not create doubt about their characters in the minds of people who see them.

Wassalam.

It is not allowed for Muslim female to show her beauty to non Mahram men. Mehindi  on hands or body can never be shown to non Mahram men.
Wassalam.

All the prophets and their divine successors are infallible and sinless as they are the best examples to be followed by human beings. Allah (SWT) ordered all human beings to obey the prophets and their successors. If God forbid, they do any sinful act, it means that Allah (SWT) is ordering us to commit sin following them, which is impossible. 
Sura al-Nasr like many other Surah have been mistranslated. It does mean at all to seek forgiveness for the prophet himself but for the Muslims who enter in the Religion of Allah for their past sins.

Every verse in Quran and every Hadeeth on this matter means that the Prophet is seeking forgiveness for the Believers.

Wassalam.

This claim came from a narration in some Sunni books from ‘Urwah Ibn al-Zubair from his aunt Aisha that the Holy Prophet (SAWA) passed away while he was putting his head on the chest of Aisha. This narration is a fabricated narration and it contradicts with authentic narrations in Sunni and Shia books . Ibn Abbas, the well known companion, denied and refuted this narration.

as it is in Tahtheeb al-Tabaqaat al-Kubra (page 402) : Abu Ghatfan asked Ibn-Abbas, “did you see the Prophet when he passed away putting his head on the chest of anyone?”

Ibn Abbas replied: “the Prophet passed away when his head was on the

chest of Ali ibn Abi Talib”. The narrator asked him, that: “‘Urwah told

me that Aisha said that the prophet passed away when his head was on

her chest.” Ibn Abbas said: “do you have sense? Can you believe it? By

Allah, the messenger of Allah, passed away and his head

was on the chest of Ali Ibn Abi Talib.”

In the well known Sunni book Al Tabaqat al Kubra (vol 2 pg 260) Ibn Sa’ad said: The prophet passed away while his head was on the chest of Ali-ibn-abi-Talib.

Ibn Asaakir, the well known Sunni scholar, narrated in his book

Tareekh Dimashq (vol 3 pg 15 narration number 1028) that the mother of

Jumai’ ibn ‘Omair and his aunt both went to Aisha and asked her about

Ali. Aisha said: “you are asking me about whom? About a man who put

his hand, when the prophet was dying, and the soul of the prophet came

out on his hand and he wiped his face with it.”

This narration has also been mentioned in Majma’ al Zawa’id by al Haythami (vol 9 pg 112)

and also mentioned by al Zamakhshari in Rabi’ al Abraar.

The false narration claiming hat he Prophet put his head on the chest of Aisha was narrated by a well known enemy of Imam Ali (AS), ‘Orwah ibn al Zubair, who fabricated this false allegation because of his enmity against Ali Ibn Abi Talib (AS) . 'Orwah Ibn al Zubair fought against Imam Ali (AS) in the Bttle of Jamal in Basra and tried with his brother Abdullah to kill mam Ali (AS).

How can Muslims believe an enemy of Ali and leave what Ali (AS) himself stated? Ibn Abi Al-Hadeed narrated that Ali (AS) himself said(ولقد قبض رسول الله وان رأسه على صدري ) “verily the Messenger of Allah (SAWA) passed away when his head was on my chest.”

Nahjul Balagah, (sermon 197).

In Musnad Ahmad bin Hambal (vol 6, pg 300) Umm Salama,

one of the wives of the Holy Prophet (SAWA), she said: “I swear by

whom I swear, that Ali was the nearest to the Holy Prophet (SAWA) and

the last person who was with the Holy Prophet (SAWA) when the Holy

Prophet (SAWA) passed away, he was alone with Ali giving him secrets

and talking to him alone.”

This is also mentioned in al Musannaf (vol 7 pg 494) also in Kanz al

Ummal (vol 13 pg 146 Hadeeth number 36459) and also in Tareekh Madinat

Dimashq and also in al Bidaya Wannihaya by ibn Katheer (vol 7 pg 397)

Wassalam.