downloading large files (>30MB) with filenames

In KS, the large file example was very helpful.

largeFile.addEventListener('click', function()
{
    ind.value = 0;
    c = Titanium.Network.createHTTPClient();
    c.setTimeout(10000);
    c.onload = function(e)
    {
        Ti.API.info("ONLOAD = "+e);
    };
    c.ondatastream = function(e)
    {
        ind.value = e.progress ;
        Ti.API.info('ONDATASTREAM1 - PROGRESS: ' + e.progress);
    };
    c.onerror = function(e)
    {
        Ti.UI.createAlertDialog({title:'XHR', message:'Error: ' + e.error}).show();
    };
 
    c.open('GET',myurl);
    c.send();
});

Unfortunately it doesn't show how to save it into a particular directory/filename. Using the clues from "Set Web View (url)" I modified the c.onload function as shown below:

c.onload = function(e)
      { // Finished downloading
        Ti.API.info("ONLOAD = "+e);
        var f = Ti.Filesystem.getFile(Ti.Filesystem.externalStorageDirectory,'tempfile.mp3');
        f.write(this.responseData);
      };

When myurl is an mp3 file that is around 18MB, this results in a file in the root of my sdcard named "tihttp#####tmp" and a file called "tempfile.mp3" in my <com.appid> subdirectory. When myurl is >30MB (I'm sure the actual boundary is somewhere in between 18-30MB), I get an error "The application... has stopped unexpectedly. Please try again (force close)". It does result in a valid file in the root of my sdcard named "tihttp#####tmp" and an empty "tempfile.mp3" in my <com.appid> subdirectory. The error is a result of the f.write(responseData) statement since the responseData is so large.

A couple (or more) questions:

1. How can I properly download large files into a particular filename?

2. Why is "tihttp#####tmp" produced? How can I write this mp3 file so that the android music player can recognize metadata? Does android clean this up? I don't want to leave large temporary files on my sdcard taking up space.

Thanks everyone!