#2
All capacitors tend to be labelled in the microfarad (uF), picofarad (pF) or nanofarad (nF) range. Conversion is:

1000pF = 1nF
1000nF = 1uf
1000000pF = 1uF

Picofarad capacitors tend to be notated by just a number.

I'm unsure about the type of capacitor you should get, but I don't believe it matters so long as you don't get a special design that does a different job (best analogy I can think of is using Zener diodes in place of Ge/Si diodes, which you basically don't do because it does a different job). And you should be able to get capacitors cheaply from a number of different online retailers - Small Bear Electronics I think are pretty good (just Google stuff).
#3
Alright, but I still can't find capacitors in a small enough range. Would be okay if I just replaced those caps with ones that are slightly different?
#4
Use same or very similar values.

For those small capacitors look into Silver Mica capacitors or Ceramic capacitors. These two types are non-polarized and come in low values.