I have seen "kacang tanah" for peanuts, although kacang with a modifier can refer to a range of beans and peas as well as nuts (legumes generally) - the only other one I've run across in limited study is "kacang panjang", long beans. Is it possible on its own it tends to refer to peanuts?
Good question. Bukan and Tidak mean the same thing but they are not interchangeable. It depends on the word they are negating.
Bukan negates nouns and adverbs. Eg. Itu bukan guan saya - that is not my dress (noun).
Tidak negates verbs and adjectives. Eg. Kami tidak suka - we do not like (verb).