This question is better answered by a customer support member from Microsoft's team, however, I think your best answer would be that it not be possible if a membership has already been added to an account.
Unfortunately, you cannot transfer game saves from one profile to another.
sorry you cant ive tried :(
very carefully
No
No, once you buy an Xbox Live subscription and put it on an account it stays on that account and can't be transferred.
I believe the next Xbox will transfer everything in your account.
Yes you have to pay money for another xbox live account but you have a one month free trial with a new gamertag.
You are allowed to create another account if you obide by the Xbox LIVE Code of Conduct and Xbox LIVE Terms of Use.
No, I do not think this is possible. Plus, I'm sure it would corrupt the data that is the original one for account b and then use account a's Xbox Live data. Not only this, I know it's impossible to have save-data and other stuff used on another account when it's account a's information.
Yes, your account should transfer.
It is impossible to transfer Microsoft Points between accounts, you can recover the account in another Xbox and download the content again for free, but you will only be able to use it with that gamer tag. (On the first Xbox downloaded all the gamer tags can use the content).
Yes, simply connect the memory unit to the new Xbox and sign in with the account.
If you account is connected to live then you should just be able to login on the new xbox. Assuming they are both 360
u don't u have to set up another xbox live account but its possible.
you can play the downloaded content on another gamertag on the same console but if u put your harddrive in another xbox the original dowloaded gamertag must be signed in a to usse the content :)