WHAT YOU DO HAVE TO LEARN
Numerals (telwoorden)
Even if you don't want to learn BI, it's very useful to know how to count. After all, this is the country of
tawar-menawar. The bad news is that counting up to ten is not enough in a country with a currency like the Rupiah. Millions and millions you'll need to know. The good news, however, is that counting is pretty systematic, structured more or less like in English.
Forms of address (aanspreekvormen) and
personal pronouns (persoonlijke voornaamwoorden)
It's very important - in any language, I'd say - that you address people correctly. The main problem here is, that this involves status and age, rather than gender (geslacht). Sorry, you'll have to learn that. Nothing I can do about it.
Verbs (werkwoorden)
Indonesians love the use of the passive (lijdende vorm). It's made using the prefix (voorvoegsel) `di.' For now, I think that's enough information. You can use the active as long as you understand when they use the passive.
Adjectives (bijvoeglijke naamwoorden)
Only one, easy rule: the adjective comes after the noun. The degrees of comparison (trappen van vergelijking):
lebih for the comparative (vergrotende trap),
paling for the superlative (overtreffende trap), both before the adjective.
Words
You'll have to learn words, lots of words. However, I'll try to compile a list of the most important ones you'll need when you travel. After all, 2,000 words is enough for the daily use of most languages, and BI is no exception.