Half-Orc Druid Favored Bonus
 

According to the Advanced Race Guide, half-orc druids can select the following ability in place of the usual "+1 HP/+1 skill point" as their favored class bonus:

"Add +1/3 to the druid's natural armor bonus when using wild shape."

When you make a half-orc druid in HL, however, you get an option that says

"+1/2 change attitudes"

I assume this is referring to the Wild Empathy ability, but I don't know where this is coming from. The AC bonus isn't listed at all.

What you are seeing is the Human Druid FCB. Half Orc's count as Human, Half-Orc, and Orc, therefore all three FCB's (if there are FCB's for druid for all three races) should be showing. As you pointed out, the half-orc FCB is in the Advanced Race Guide - which you probably do not have enabled. Go to Configure Hero (CTRL-K) and make sure it is enabled, and the proper options should be available.