So I'm trying to decide if I even need to bother with the whole plumbing
in the basement thing. I never had a bathroom below grade before. I
understand that there is a pump that has to be kept on all the time (or
when someone flushes?).

Since its a Nationwide builder and they re building "basement homes" I'm
guessing that the lots are set up for sewer. Given that the homes are
planned with a basement and bath down there, around here that means that the
sewer is below the level of the basement and a pump system wouldn't be
required. In Urban/suburbs this is the way it is here..to require a pump
etc would indicate the home is "out of town" where most big builders aren't
working and perhaps a septic system, neither of which works for big
builders, new developments here. No sewer, no basement say the local codes

R