Nice poll!
2. For a Legendary member, receiving Merit should have a restriction or (may be just) don't apply Merit for them
I believe Theymos has ruled out preventing Legendary members from receiving merits. So my suggestion is to make legendaries receive 1 sMerit for every merit. It may allow some abuse of the system but it would put their accounts on the line and I don't think that would be a wise move of a Legendary member.
Anyway it's not actually a "hole" in the system. Lets say 10% of merits are gone to Legendary members every month. Increase merit generation by sources by 10%, problem solved! So it doesn't actually need a specific solution.
This special privilege is not required at all. Suppose there is a member here with two legendary accounts. He can generate as many merit points he wants if the suggestion you said was implemented. Most of the senior members are responsible enough but we may have sale of accounts happening frequently. Sometimes the accounts also get hacked and if a scammer has access to such accounts, he will abuse this privilege.