I am building a new house, and as an almost afterthought, I want to install
prewiring for an alarm system. I am thinking of just prewiring the system for
now, and purchase the system/subscription later. The drywall is not up, so
this should be reasonably easy to do.

System wise, I don't want to commit to a particular system/vendor yet, and I
want flexibility of choosing from different provider later. I assume that all
the wires are compatible amongst the many different systems (ie, the three
wires for power, ground, and signal, same gauge requirements, etc)? If not,
what should I look for?

What can I expect to pay for this? How do I spot a good installer? What
questions do I ask? How many sensors should I install (I am thinking all the
doors, all the windows, fire, water, smoke, low O2 (is there such thing), what
else am I missing?)?

Thanks.