How to get there?!?

Hello everyone, I'm new to the site and this is my first post. I'm planning a trip to New Zealand (I'm from the states) in November and so far I've worked out that I'd like to tramp the Tongariro North Circuit, do a combination sea kayak and tramp in the Abel Tasman, and maybe one other great walk in the south. I've found this site and a few others I've found to be very helpful for route descriptions and such, but I'm having a hard time finding advice and options on getting to the track. For instance, my plan is to arrive in Auckland and take an InterCity Coach to Taupo. From there the best I've found so far is bus service intended for folks doing the Tongariro Alpine Crossing. it'll drop me at Mangatepopo but as far as i can tell I'll be on my own to get back. I'm sure there are shuttles or buses to and from Whakapapa Village (whomever wrote the wonderful track report for the Circuit mentioned a shuttle to the train) but I haven't found them yet. Am I worrying needlessly? Although I'm very experienced tramping in the backcounty here in Colorado, this is my first time in NZ, and first backpacking trip abroad. I'll be traveling solo. Does anyone have a suggestion as to where on the net I'll find the right business to get me to where i want to go. I certainly plan on trying to hitch it, but you can't always depend on the generosity of strangers. Thanks!