For your first question, read this:
http://www.smwcentral.net/download.php?id=111&type=documents
for your second question, I think those use the same GFX as the rest of the letter tiles (GFX 28, make sure you set to 2BPP) but it just uses the regular letter tiles, not it's own committed tiles, so if you want to change what it says, you should use this tool:
wait... not that tool... this one:
http://www.smwcentral.net/download.php?id=13&type=tools