By train arriving at either Interlaken Ost or Interlaken West. The tourist information center is located at the ground level of the MetroPole Hotel, in between the two stations. If you intend to head up to Bernese Oberland, alight at Interlaken Ost and hop onto a connecting train to Grindelwald or somewhere up there.
The Bernese Oberland regions are connected to one another by cable car systems, funicular and mountain rail tracks. To figure out how to go from one region to another, pick a copy of the ski trails map and it will tell you all.
To get to Schilthorn the best and only way is by train, cog railway and cable car. With the Swiss pass the trip is only 40SFr. The view is Spectacular, and some say better than Jungraujoch. With your Swiss pass you can get to the town of Murren which is also breath-taking. THe extra 40SFr is worth it though. You feel like you are at the top of the world and nothing can stop you.
you can reach thun via zurich or berne airport and take the train from there to thun. from zurich it'll take around 2 hours, from bern 30min.
thun has a little romantic old city center - you dont need transportation when you're in thun - just if you want to go to the places around thun you can take the bus, train, ship...
I noticed Thun had an excellent mobility scheme. Cars by the station were available for hire and also near to the old town bicycles could also be rented by the hour or day.