Agreement of Sale optional inspections

I have kind of a dumb newbie question.  I've got the agreement of sale for a property that I'm about to purchase through a turnkey provider.  At the end there is a list of optional inspections that I can either elect or waive.  Some of these items are not particularly relevant to the area or seem like they would be costly to execute.

Two questions:

1.  Should I be electing all optional inspections?

2.  Once I initial under "elected" for a given inspection, am I then legally obligated to have that inspection carried out, or am I simply reserving the right to do so at my discretion?