The sticker looks great! But you have used color 383 for silver, should use color 80 (for more details, see this discussion http://forums.ldraw.org/showthread.php?t...214#pid214 ). Too bad LDraw doesn't have yet a holographic color for background 
No, 4215pb003 is wrong, you created it as a pure patterned part. What you might create is a shortcut with sticker attached, using 4215 + 168275 and name it 4215dxx. See http://www.ldraw.org/cgi-bin/ptdetail.cg...181d05.dat as an example, and http://www.ldraw.org/Article512.html#stickers for standards.
Now if (virtually) applying sticker is easy, I would not create the shortcut to avoid cluttering the library...
No, 4215pb003 is wrong, you created it as a pure patterned part. What you might create is a shortcut with sticker attached, using 4215 + 168275 and name it 4215dxx. See http://www.ldraw.org/cgi-bin/ptdetail.cg...181d05.dat as an example, and http://www.ldraw.org/Article512.html#stickers for standards.
Now if (virtually) applying sticker is easy, I would not create the shortcut to avoid cluttering the library...