If a child has reached the age of puberty, then hajj is compulsory for him under his guardian's supervision.
Mahram is a person to whom a person cannot marry. It can be,
You can pray by using this sequence,
Men have two options, either to trim or to shave their all hairs of the head. Trimming is better but both are allowed. Women should cut only 1-1.5 inch of hair.
No, fasting is not valid because it is the day of tashriq, and 10th, 11th , 12th are the days of Qurbani (nahr) in Islam.
Haji (pilgrim) is not allowed to cut his nails and hairs before Qurbani as there are some restrictions to do or not to do while wearing Ihram.
Two rakaats prayer while wearing Ihram is Sunnah. Jabir (may Allah be pleased with him) reported that when Holy Prophet (S.A.W) wore Ihram, he offer two rakaats. Surah kafiroon should be recited in first rakaah while surah Ikhlas should be recited in second rakaat.
Hajj not only remove minor sins, but also eliminates our major sins because in Hajj, all other four pillars of Islam are also included and we become closer to Allah.
Yes, according to most of Islamic scholars, Umrah performed in the month of Ramadan is equal to Hajj especially the one that is performed in the last ten days of Ramadan.