How do I make a beam maintain the offset I have given it?
By default a beam will Cleanup so that the top of the beam is level with the top of the wall it intersects with. If that is not desired, when editing the offset of the beam uncheck the Cleanup box and the beam will now maintain the given offset.
Is there anyway to specifically locate a post that is under a beam without moving the beam?
Yes. After selecting your function (Move, Edit, Item Extension), click on the Misc > Locate Type > Post. This will isolate the post as the item to select. Note: Ctrl+L can be used to open the Locate Type menu after selecting your function.
Where is the offset of a post and pad measured from?
The offset is measured to the underside of the post. The pad has no bearing on the offset measurement.