you're welcome - iie (ee-yay). Literally it means "no," like the spanish equivalent "de nada," it's nothing.
In other words, Arigatoo / Iie are like Thanks! / Oh, don't mention it.
mad is a verb, not an adjective. People "get mad." okoru.
silly - how about omoshiroi ? That means "interesting" but also "funny." If you mean absurd, bakabakashii.
(hungry) You have to say stomach-subject got empty. Onaka ga suita. "ga" marks the subject of the sentence.
"suita" is past tense of get-empty.
(thirsty) You have to say "throat sbj got dry" which is Nodo ga kawaita.