Salamun alaykum

Yes this practice is considered as gambling. In general any practice which involves a prize achieved from the property of the participants is gambling. 

Bismihi ta'ala

Many different explanations have been given regarding to the two terms shaf' and watr, as they have been used in the holy Quran (surah al-fajr, verse 3).

Al-Shaf' is usually translated as the 'even number', and al-watr is translated as odd number.

One meaning given is that all creation is made of pairs, and Almighty God being Singular.

Bismihi ta'ala

The case of Imam Hasan al-Mujtaba (a.s.) having married a large number of women, and also excessively divorcingو is a topic that can be approached from different angles.

The claim is that Imam al-Mujtaba (a.s.) was a Mitlaaq, which means someone who excessively divorces (from the word talaq). 

There are some narrations that hint to this in certain Sunni hadith books, which, for Shi'a, do not carry recognition, based on its sources and also other hadith related principles.

Bismihi ta'ala

According to the main view the word 'Ameen' آمين is used to mean 'O God, answer'. So, in this case there is nothing wrong with the expression itself, even though this word does not come from the Quran, nor is it a part of any verse. 

This is something agreed upon by both Sunnis and Shi'ah. 

However, the issue is whether it is permissible to say it in a daily obligatory prayer, after reciting the Fatihah. 

Bismihi ta'ala

Besides the shar'i side of when and how Hajj becomes obligatory, I would like to add that Hajj pilgrimage is a life changing experience. 

As Muslims we face the holy Ka'bah on a daily basis. We relate very much to it, and if we were to visit it we will expand in our visualising of this relationship we have with the House of Allah ta'ala. 

This is why travelling to Meccah al-Mukarramah at an early age will have a great impact on our identity and mould our religious personalities.