RE: Squat on Self Spotter
If you use a squatting rack you'll be just fine without a spotter. Just don't lift to failure.
Worst case, if you drop the bar or fall down, depending on the type of rack you have, it'll catch the bar before it falls on you.
The Smith Machine is really bad because it forces you into a straight up and down motion...that's unnatural. Also, you're not getting a lot of stabilizer muscles activated, so your growth will be minimized.
Anyway, there's just something about tossing a couple hundred pounds on your shoulders and going at it.