Survival Japanese

So far my main struggle in Japanese has been worrying about how to say things politely. Polite language is quite complex in Japanese, not unlike the complexity of polite English modals (e.g. "Could you please" and "I would like to..."). I hope I get it soon! I hear a lot of the polite ending います (imasu) in my everyday dealings, so for now at least I am recognizing politeness when I hear it.

I'm a firm believer that vocabulary must come first in language learning; with vocabulary, you can at least scrape by on Tarzan-speak. Then, the more sophisticated grammar can come next. We'll see if my theory holds up to reality in the coming months. If nothing else, I'm very glad I've got a passable foundation in the basic "starter pack" of vocab: household objects, numerals (ichi/ni/san as well as hitotsu/futatsu/mittsu), please, thank you, excuse me, etc. It also helps immensely to read katakana, the script for loan words!

Here is a selection of what I've been hearing and using the most. Sadly, yes, "cockroach" is one of them.

おねがいします — a polite form of "please"
いたします — a polite form of "to do"
車 — kuruma — car
道 — michi — town
車道 — kurumamichi — My neighborhood. :)
ゴキブリ — gokiburi — cockroach :(
べつべつ — separate (for checks)

Please come in. お入りください. (ohairi kudasai)
My Japanese is bad. 私の日本語はだめです。(watashi no nihongo wa dame desu)*
How much? これは、いくらですか。(kore wa, ikura desu ka)
Excuse me, do you speak English? すみません、英語が話せますか。(sumimasen, eigo ga hanasemasu ka)
Is it/this OK? だいじょぶですか。(daijobu desu ka)
Excuse me/Sorry! すみません (sumimasen)
I'm sorry (I did that)! ごめんなさい。(gomen nasai)

* - Edit: I'm not sure this would be the right way to say it.