Even if you're paying a lot of taxes now, you're talking marginal dollars when you look at current contribution, and average tax rate when making withdrawals. (money.stackexchange.com)
Yes you will receive the interest amount on accumulated (carried forward + current contributions) balance. (relakhs.com)
While 529 college savings plans are intended to encourage long - term savings, the ability to deduct current contributions creates a loophole that encourages short - term savings. (finaid.org)