I'm not exactly an expert, but I did find myself searching for answers on acid blends recently. Not really sure about eliminating alcohol hotness, I think that mostly will only come with aging. What I did find is that with the right amount, acid blend can take a flat-tasting mead and add a little bit of complexity. I currently have a 3-month old pear melomel in the works, but it tasted a little flat and overly sweet for my taste. After adding 2 teaspoons of acid blend (for 1 gallon batch), it perked it up and added a slight "bite" to the sweetness. It's also very easy to overdo it, so I would suggest taking a few small samples of the mead and testing out different amounts of acid blend in each sample, then taking the one you prefer and scaling up to match the amount you need for the rest of the batch. Just make sure you do the math right, if you add too much it can get very sour very quickly! I read that it's recommended to add the acid shortly before bottling, and I've also read that you can add it during bulk aging... but the consensus seemed to be that you definitely want to wait until fermentation is finished. After using it on this mead, I'm definitely looking forward to using it on future batches that might need that little extra touch of complexity. Hopefully that helps a little bit, maybe someone else can chime in.
Cheers!