I booked my car through Kasina. I think it was about $250USD total w/ insurance for 5 days. I picked up and returned at the airport.

I booked the jet boat through the Andaman concierge. I think it was about $50USD (little over 200 ringgit), which included car transfer to and from (about 40 minutes each way). The concierge was very helpful and prompt. You may be able to book directly through Naam.

Not sure about hiking. I like hiking as well, but we didn't end up doing much except walking around the resort and along the beach. There's a hike at the hotel which we started but promptly turned back since it was a bit more wilderness than we wanted (GF does not like massive spiders!).