i.There is a cadency label on the inescutcheon of Alfred's Arms (which are his Arms in right of the UK).
ii.The Arms of junior members of the Russian Imperial family did not use marks of cadency and were not differenced on the shield but by the external ornaments.
iii.I see what you mean as regards the Arms of Scotland in Alfred's Arms-that is either a mistake, or that part of the Arms has been damaged in some way.
iv.That is the Russian Imperial eagle-a double headed Eagle Sable on a field Or, with an inescutcheon Gules depicting St. George on horseback slaying the dragon.