Tempelhof is a free public park, there are no official tours I know of, except maybe for bird watchers. The building is not accessible.
The 100 and 200 bus lines can be used with normal tickets, if you buy day or multiple day tickets for public transport, you can hop on and off as desired.They´re normally serviced by doubledeckers.
Sure there are no explanations on bord and some places of interest are not covered by them, but if you already helped yourself with explanations in advance you may rely on public transport anyway.
Most of the beer in Germany is served as "Pils(e)(ner)", which is a bit more bitter than lager. Other than anywhere else, a "flower" of firm foam is a sign for quality-tapped beer, which should last a few minutes to prepare.
A refreshing special Berlin kind of beer is "Weiße" (white beer), which has a sour taste and therfore is served with red ("rot"/raspberry) or green ("grün"/woodruff) syrup, ladies like it.
Currywurst is one fast food invented in Berlin, the other one is "Döner" (Kebab), created by a turkish Berliner.Especially in May restaurants serve white asparagus ("Spargel") dishes.Germans are mad about this vegetable.
One thing for Sanssouci: public transport in Berlin is ticketed by 3 zones. Within Berlin borders you travel with AB tickets. Since Potsdam is outside, you need either an ABC ticket or a "C-" enhancement for AB-tickets, available on machines in advance, one for each direction.Same counts for Schönefeld (SXF) airport.
The whole Sanssouci complex is a vast park, be prepared to need a whole day.
Hope to be of help