Either is grammatical, according to the Cambridge Grammar of the English Language (Huddleston and Pullum 2002).
The comparative determinatives more, less, fewer can occur after the head provided there is a determiner. Thus we have a post-head alternant for one more day but not for more days: compare [One day more]/*[Days more] will be needed.
"Two items fewer" is ungrammatical because fewer refers to the number of items, rather than the items themselves. Therefore, "two fewer items" is correct.
two fewer items
is correct, meaning the count of my items is two lower than the count of theirs.
Page 974 of Garner's fourth edition reads
Two worst, not *worst two: the first, which is more logical than
the second, has always predominated in print.
I do not why the first one more logical though. According to Google ngrams, we say the two best/worst but the first/next/last two.
It has to do with the order of adjectives. Look here to see the order.
The worst two foods are eggplants and doughnuts.
is incorrect, whereas
The two worst foods are eggplants and doughnuts.
Even though many people (including me) have never formally learned this order, we tend to adhere to it just from experience.
Even though it may be a ...
The 1st sentence is not lucid enough. The if any applies to What which also points to benefits and disadvantages.
The 2nd sentence is the best way- it avoids ambiguity and also since the intent is to ask if there are any benefits or disadvantages of something. The 1st sentence and 2nd sentence mean the same.
The 3rd sentence says: if there is 'something',...