I think I should move to New Zealand!
There are many ways to have a bad experience here. One way to maximize fun and minimize risk of problems is to join this site and pay for VIP membership. By doing a bit of research here, reading reviews and so on, you can avoid the fakes and danger zones that are out there.
Yes, most reputable providers here will screen you. When you don't have any references, the best thing you can do is to also join a verification site like Date-check or P411. This may require personal or work info and maybe a fee, but it will also get you "in" with many providers with minimal hassle.
Most reputable providers will give you a rate for their time and will not require tipping. Tipping is not a bad idea if you can afford it and think you may want to see the girl again, it's just a nice way of saying thank you. Agency girls pay a good chunk of their earnings to the agency, it's an especially nice gesture to tip them.
Some offer incall, some outcall, some both. Some actually xharge extra for the incall. It's al based on their own formula.
You cannot discuss specific services on preliminary phone or email contact. Most providers will hang up on you and refuse to see you. If you want to know what she offers, read the review, that's the whole point of the review.
Read the self help center (life preserver icon) for much more info. Good luck.