I always try to use free weights... It works your muscles better in terms of having to balance and controling the weights in each motion... I use the machines if I don't have a spotter though... much rather do that then be found pinned under a barbell. lol!
As far as a trainer, if you want to spend the money go for it- I have learned a lot by just doing my own research and asking other weight lifters questions... I think most of it comes with practice anyway- you will get to figure out what works for your body best... only you can feel the burn anyway.... Alot of the basics are the same just don't go too heavy and research the proper forms, and go from there...
As far as looking like a body builder... most of those guys are on steriods and consume a hellacious amount of protein... keep in mind your diet has a tremendous effect on what your results will be
good luck!