All the following are only effective in darkness:
Shade benefits (in darkness):
+20 Speed
+4 AC
+2 Attack & Damage
-10% light per level
Fast Healing 2
Invisibility 1/Round
60’ Darkvision
Shadow Image 3/day (d4+lvl/3 images - as mirror image)
Spell Resistance 11+lvl
+4 to all saves
+2 Con, +2 Cha
+4 Listen & Spot
+8 Hide & Move Silent
8th level: Shadow Stride (Dimension Door 300 ft. every 2 rounds)
12th level: Teleport Without Error / Plane Shift 1/day
Can't help you with the ECL, but the CR's +2. ECL could be +4 or +5, depending on which book you read.
(You're just lucky I had it typed up for a high-level shade monastery my players are going to run into!)