Thanks for everyones replies. I realize wal-mart bikes are junk, the
bike was a gift from back when I never really rode much (and when I
wondered why people had bikes with such thin tires).

As for riding with the traffic...
I try to stay in the shoulder at most times, but the roads without
shoulders (or with shoulders filled with sand/glass/tar) are usually
on one-lane roads where passing is prohibited. Is it best to stay in
the traffic lane until I find a safe/clear shoulder and then signal
the car(s) behind me to pass me? Also, at major intersections without
left/right turn only lanes, (like US6 which I cross now and then) I
assume it is best to get in a lane, rather than try to ride along the
side where someone going straight could hit me, correct? I see people
on road bikes moving with the traffic, but I just see everything a
little differently as I can't move that fast. Also, I always ride on
the right (with traffic flow).

I bought the GPS because I wanted it mainly for in-car
directions/mapping on my laptop. I just got one with a display and
some extras since I could use it while biking. Also want to get a
speedometer/odometer eventually, GPS has one but standalone is nicer
(had one but it broke a long time back).

As for replacing the tires - will those thin tires be able to support
my bike? The frame is steel and the entire thing is damn heavy
compared to a schwinn my mother used to own (that went in a yard sale
years ago). Might just wait a few months until I have some more cash
toward it and look on ebay/bike shops, with 2 gears working and one
that fails when you need it (dosn't lock and you end up having to walk
it across an intersection at times), I may just hold off and buy a
completely new bike.