Does a man show his right shoulder while wearing his Ihram attire?
No- he shows his right shoulder when he begins the Tawaf and during the Tawaf,then he covers his right shoulder after finishing the Tawaf.
What is the Ihram attire for men?
Ihram attire: Izar– what covers the lower body and Rida’– what covers the upper body and is placed on the shoulders
What is the ruling on one who has passed the Meeqat without wearing the Ihram attire, because he was sleeping on the plane due to fatigue from traveling?
All he has to do is wear his Ihram attire when he wakes up with no need tosacrifice, as his mistake was unintentional.
Is it permissible to wear the Ihram attire from home, before getting on the airplane?
Yes, this is permissible and allowed as part of the flexibility of this worship act.