This gets you all of the metadata directly available to Mathematica:

Import["ExampleData/rule30.wav", #] & /@ {"AudioChannels", 
  "AudioEncoding", "SampleRate"}

And this gets you the number of samples:

Length[Import["ExampleData/rule30.wav", "Data"][[1]]]

Bits per sample is a bit more complex, but I think this should be what you're looking for:

N[(Length[Import["ExampleData/rule30.wav", "Bit"]])/(Length[
    Import["ExampleData/rule30.wav", "Data"][[1]]])]

I don't know if there are any import limits or restrictions in M8, but M10 loads an 18mb file without a hitch. It's probably either the older version or some kind of memory problem on your computer. Could you post the message Mathematica fails with?

This can be automated

fileName = "one.wav";
ele = Import[fileName, "Elements"]

Which gives, for this file

  {"AudioChannels", "AudioEncoding", "Data", "SampledSoundList", "SampleRate", "Sound"}

and now

 all = Import[fileName, #] & /@ ele;