Walk through all files in a folder and do this for all subfolders and...

Question

... and their subfolders, etc. I mean I want to recursively walk through all subfolders of a folder and when I'm "in" in each folder I would like to walk through all files alphabetically of that folder.
While iterating through the files (of a certain type: .mp3, .mp4, .m4a) of that folder, I need to make a simple counter. e.g. when counter is 3 it means we are on the 3rd file alphabetically of the folder.
Then I simply want to set the track # mp3 tag of that file to this counter value (e.g. 3)
Anyone know how to do this? or at least to be able to show me the walking the folders and iterating the files bit? I'm brand new to applescript.
Why do I want to do this? Well I have a lot of live music shows, each in its own folder, but in my apple devices and itunes when I play a show it will not show the songs in the correct order. The file names are alphabetical in the correct order though and I suspect if I assign track #s then itunes, ipods and iphones will be able to play the "album" back in the order listed by track #??

Answer 1

What are you using to play your items? iTunes can use various properties to sort a playlist, independent of what the file name is (Finder too, for that matter). If you are just wanting to add a prefix number to a file name, you would also probably need to use leading zeros to keep it in order when sorted by name.
The following is a general purpose handler to go through the items in a folder - I just put various text into the output list as an example.
<pre style="
font-family: Monaco, 'Courier New', Courier, monospace;
font-size: 10px;
margin: 0px;
padding: 5px;
border: 1px solid #000000;
width: 720px; height: 340px;
color: #000000;
background-color: #FFEE80;
overflow: auto;"
title="this text can be pasted into the Script Editor">
on run -- example
set TheFolders to (choose folder with multiple selections allowed)
choose from list (ProcessStuff from TheFolders)
end run
to ProcessStuff from SomeItems
process items contained in SomeItems, recursively descending the directory tree
parameters - SomeItems [list]: the items to process
  returns [list]: a list of processed items
set FilesList to {} -- this will be a list of processed items
repeat with AnItem in SomeItems
set AnItem to AnItem as text -- get the contents
set FileInfo to (info for AnItem as alias) -- see Standard Additions
if (folder of FileInfo) and not (package folder of FileInfo) then -- a folder (not a package)
-- do something with the folder, if desired
set the end of FilesList to "folder  " & AnItem
try -- sort and process contents, skipping any errors
tell application "Finder"
set SubItems to (get items of folder AnItem)
set SubItems to (sort SubItems by name) as alias list
end tell
set FilesList to FilesList & (ProcessStuff from SubItems)
end try
else -- a file
-- do something with the file, if desired
set the end of FilesList to tab & (name of FileInfo)
end if
end repeat
return FilesList
end ProcessStuff
</pre>