TextAsset asset = Resources.Load<TextAsset>("Filename");
Stream s = new MemoryStream(asset.bytes);
BinaryReader br = new BinaryReader(s);
Notes:
don't add .txt to the string filename passed to Resources.Load
do add .txt to the actual file
use BinaryReader.ReadSingle() to read in a 4 byte float
use BinaryReader.ReadChars() to read in characters