Tongan language: generally like Hawaiian, but without the harsh "iki" type of sounds.
Instead of "ma-halo", they say Malo e lelei ("malo-eh-lay-lay"). You can respond by saying "fefe hake" (fay-fay-hah-kay) which means "how are you?" and then they will often respond by saying "saipe" (sigh-pay), which means "fine". "thank you" is malo (mah-low); but better to say "Malo 'aupito" (mah-low auw-pee-tow) "thank you very much"
No such thing as a "howlie" in Tongan. Instead, white people in Tonga are called "Palangi"..which (roughly) means "the people in white ships"
Tonga (as the Tongans will tell you), is also known as the "friendly islands" because captain Cook et. al were heavily feted during their visit, while the Tongan princes argued (behind the scenes) as to the best way to kill Cook and all his men and take their ships. They never could decide, and Cook sailed away before they could kill him. In the meantime, everyone had a really good party; so not a total loss.
some resources for the language:
Tongan language learning games
Useful Tongan phrases
Tonga: Important Phrases - TripAdvisor