Hi Tide88 and welcome to our community
I think you might benefit from a class on RoboHelp. I'm not
being ornery here, just stating that you seem to have a
misunderstanding of the way RoboHelp is designed to work.
Conditional Build Tags are a feature that you use when
creating the help file. They aid you in creating customized
versions of a help file. Typically by excluding things. Where you
are misunderstanding here is that you seem to think you may employ
them after the help file is built. Perhaps in order to achieve some
sort of a dynamic changing of views.
The same goes for a "predefined search". There actually is
such a feature. Most of us would call it the Index function. it
allows us to choose any "search term" (AKA Index Term) and
associate it with any number of topics.
Hopefully this helps a smidge... Rick