You are correct to file MFJ, as that will give you the most for education credits. But as to who gets what, the tax forms don't work that way. A joint return is just that - joint. Meaning that a single check is issued with both filer's names on it. If a direct deposit, most banks will not accept a direct deposit to joint recipients, if the names of both recipients are not on the account. Not all banks are like that though.
How odd. My wife and I put our (occasional) refund in our joint checking account because we're married.
Yes, "joint" means just that, both, not "mine" and "spouse", but together.
What you can do is to do a return for him as though he were single and one for you as though you were single. Then a joint return. It may turn out that the refund on the joint return is actually less than if you were both single. Or it may be more. But it may still guide you as to a "fair" allocation. If you file Married Filing Separately you will get no education credit and you cannot legally file as single.