Howdy and welcome to the forums.
Looking for work is a bummer. Been there, done that, good luck with it.
I started riding with a $100 mountain bike from Academy that was probably of similar quality to your Huffy. Maybe worse, since it was newer. Anyway, I'd try to keep the thing rideable, but not really upgrade, either. You're better off saving any upgrade money for a new bike. It's hard to say on frame size. Department store bikes in general tend to be on the small size, as a small frame is more of a one-size-fits-all frame. But mountain bike frames are usually intentionally lower than road bike frames, so the fit is not identical on all styles.
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"be careful this rando stuff is addictive and dan's the 'pusher'."