Funny you mention this, I was just about to post a question about Buffer 5.2. From everything I'm aware, acid malt just acidifies the mash, so in that case Buffer 5.2 would suit just fine (although don't quote me on that).
IMHO, not really. I only use when I brew my Dry Irish Stout. It contains lactic acid and lowers your pH. It gives it that "Guinness twang". You might try to sub with Melanoidin to give it some fullness. Some people add a soured beer to the wort when brewing this style.
I typically use 5.2 Buffer in all my beers. I was going with BierMunchers recipe, which calls for .25 lbs in a 10 gallon batch. This beer is being given away to a guy that supplied me with about 2 bushels of hops last fall. I typically force carb, but this will be bottle conditioned. I do not suspect he will leave this beer alone long enough to let the sourness mellow a bit, so perhaps I should just skip it all together?
You prob don't have the time,but you can pour a warm can or two into some tupperware mix in a handful of cracked grain and let it sit out, open, on the counter a day or two.
Strain the grain and add it to the last 10 min of the boil.
That's what I did on my recent guinness clone. It's not fully carbed yet but tasted pretty close.
i use 1/4 pound of acid malt in my grists to lower the pH a little- hit 5.2 dead on the last few batches
although the acidity in the mash is the main characteristic of acid malt, it can also significantly improve the head of the beer, important in a stout where you want a fine, creamy head instead of a coarser, faster head
As to drinking it young... I did BierMunchers recipe on a 5 gallon with the acid malt and it is bottled... young, but drinking fine. The flavors are very distinct, which I think will mellow together pleasantly with time, but it is not unpleasant with that amount of acid malt. It is currently three weeks in the bottle.