i think so! this is a common linguistic phenomenon known as zero coupla, and it also occurs in turkish, japanese, and some dialects of english, among many others. it's important to note though that even in languages with zero coupla, "to be" can only be dropped in certain contexts -- like how in Russian быть can only be omitted in the present tense. i don't know enough about indonesian to say, but i'd guess that other tenses require "to be," so don't get too used to leaving it out :p

Seems like it. The only difference is that adjectives don't have gendered endings in Indonesian (at least that's what I think)

"Adalah" is the word which has the closest meaning with to be, yet it is only followed by noun (not adjective)

да