I dont understand how the E is used, in the previous sentence it was "E lei" to give a lei, but "E 'ai" is to eat?
E in this case indicates that the verb is a command/request. E in other contexts can be used to indicate subject. Words in Hawai'ian are very fluid
I think "e" is similar to the verb "être" (to be) in French, but that is only based on the context I have seen so far.
Yeah lol, imagine how confused a Hawaiian would be if two Brazilian tourists just saw each other in Hawaii and were like "e aí?"