Logan,
I'm sure it would be no problem to join and buy the tix on the same day--but $50 for membership (that's what it is in Michigan, give or take $10) just to get a discount on something you'd be able to do in another 5 days anyway, to me, at least, seems extreme. You'll end up losing at least $20 (after taking the discount of the tickets into consideration versus the cost of membership, and not including travel time and expense to get to an AAA Ohio location), net result. There are also residency restrictions to consider--you might need to be a resident of Ohio to join AAA Ohio (I can't comment with certainty on that matter).
As for your second question, that might be a matter for individual branches to determine. But then again, there might be a statewide policy regarding this issue. Some might let you buy unlimited numbers, but, with limited state-wide availability, it's my guess that there will be a limit. Shouldn't matter, though, if you're buying for non-AAA members (how would they know anyway?).
I don't know about the age requirement. My guess would be if you're old enough to drive, you're old enough to become a member of an auto club. They might think differently, though, what with 18 being the age of adulthood and all that.
You'll notice there's lots of uncertainty in this post--me hedging lots of my own comments. The only way to answer any of these questions with definition and authority is to call AAA Ohio or one of it's branch offices and take down names when/if you get the answers you want to hear. What they say is golden. Anything you read here is speculation--pure and simple.
John
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