You can reach Oberammergau by train from Munich central station (München Hauptbahnhof). You have to take the train headed to Innsbruck (a regional train that departs on daily basis) and switch trains in the Murnau train station (the train to Oberammergau is the only other train in the station). The trip from Murnau to Oberammergau shouldn't be a problem, since Oberammergau is the last station to be reached.
You may also reach Oberammergau by car. You would have to go to south Munich in order to the take the Autobahn A-95 south to the Ettal exit. From there you go on the B-23 to Oberammergau.
Getting around Oberammergau shouldn't be a problem since it's a relatively small town. You can get around (as most locals do) walking, but you can also take the bus (there are a couple of bus stops in town). You can also get around by car and (like most of the youth) by bicycle.
If there is something that anybody who has been to Oberammergau should have it is a wooden souvenir. Wood carving is an ancient art practiced in Oberammergau (there's even a couple of schools in town). A usual Oberammergau souvenir is a wooden crucifix. There are two kinds of wooden clocks that can be purchased, the first a cuckoo clock (which may vary in size and price) and the second one a Bavarian clock, which goes in the opposite sense of conventional clocks with the inscription "In Bayern gehen die Uhren anders" (In Bavaria the clocks run differently).
For a small town Oberammergau offers a great variety of places to eat. If you don't wish to spend too much money on food you can try eating at one of the imbiss (bars in which food is also served). You can also eat at one of the many hotel and guest houses (where among international food, local food is also served - the Hotel Maximilian is particularly good for the latter, and has a very nice atmosphere too). There are also classical choices of food, for instance you can try El Puente (a Mexican restaurant). Desserts are to be found not only in the restaurants but also in some cafés.
Hot beverages are served in the small cafés in town. There are also Café/Ice shops in which coffee and ice creams are sold all year round, but if you'd like to have a nightcap then you probably would want to go to some of the town's bars. If you're young and just want to relax among young people you should go to the Kino Cafe (a movie theater with a café). In here you're most likely to find any kind of cocktail you want and also some good food, but if you want to experience some of the local folklore then Zum Tonis is the right place for you; a typical Bavarian bar, with a friendly staff and a large variety of local and international schnapps.
For such a small town Oberammergau presents quite a variety of hotels, with prices between €45 per night to €200 per night. Location is really irrelevant since the town is quite small. Some of the hotels are pretty basic in what they offer. You can stay in places like bed and breakfasts (which have a more "family-oriented" feeling to it) or you can stay at a 5 star hotel like Maximilian Hotel. You may also want to consider which hotel is adequate for your needs. For instance if you're traveling alone, if you're bringing children with or even pets, because some hotels are more suited than others.
For backpacking travelers you may want to check the local Youth Hostel out. It has 29 rooms, conference rooms, winter sport equipment rental, and you are able to have breakfast (buffet), lunch (buffet), dinner and packed lunches in the hostel (they will take into consideration the nutritional requirements of different cultures and religions, if such requirements are cleared when the booking takes place). The price of a hostel room can vary from €17 to €25 per person, per night (the variation comes from including meals in your accommodation). Please note that this hostel closes over the winter, so check whether it is open when you plan to go.