I read that cataclysm made a lot of changes to 1-60 leveling, new quests, changing of zones etc. If I were to buy only the first WoW would I experience the same 1-60 leveling as a cataclysm user would have? Or would the zones look the stock WoW before the expansions changes.
It would be the new Cata zones & quests. Most of Cata was realsed through updates/patches. So you would see the new Cata visuals, have the new updated quests and play through the changed zones. You wouldn't be able to fly in the original zones at 60 though without the expansion. Also I don't think that you'd have the oportunity to learn the updated profesions either. All in all, yes you could buy & play just the "original" game minus the expansions and experience the zone changes & new quests.
Just a question though, why not buy & install all of the expansions in one shot? I believe that Bliz has the first 3 installments at a reduced price so you'de only be paying full price for Cata (believe me it's well worth it) and it costs the same monthly subscription fee regardless. Just a thought.