The train station is underneath the Zurich Airport Center (Bahnhof Zürich Flughafen) It is an easy and fast train ride to Lucerne, so there is no need to spend the money on a private transfer. The SBB site is very user friendly, so use that to check for schedules. I believe you should consider staying in either Wengen or Murren, rather than Lauterbrunnen. Both are car-free villages, and IMO give you a better experience of staying in the Alps than you will get in Lauterbrunnen. We chose Wengen, and loved everything about it. There was construction going on in Murren, and I am not sure when that is expected to be completed. We are not big hikers, but from Wengen, we were able to take the mountain excursions that best fit our interests. The cable car to Mannlichen is a 10 minute ride, and once there you can enjoy the views and take the Mannlichen Royal Walk which is not at all strenuous. You may also want to research a trip to the Schilthorn. After the Schilthorn, you can take a lovely, scenic walk from Murren to Gimmelwald, which is a quaint little Swiss village. Wengen has a COOP next to the train station, making it very convenient to pick up items for a picnic lunch. We found this very helpful in stretching our food budget, since Switzerland is quite expensive.