yes most people here trade currencies and then one day start commodities and other things and pif paf puf start earning money.
no you dont buy gold. in fact trading with a cfd broker, which you are, means the same like trading currencies. you bet on the change of price but do not participate in the market at all. most brokers here used for forex trading are offering cfd's on commodities and indexes. these trades are solely and purely dealing desk trades so in 100% of cases you trade/bet against your broker.
if you want to participate on the market you must go with futures contracts or warrants and options.
there are many advantages trading commodoties. the spreads are tiny and the moves are bigger than in currencies. the market is not manipulated 24/5 like currencies and is based solely on supply and demand (besides gold, that is in itself a currency mixed with industrial demand). the margins i can not compare since i dont trade currencies but from what ive seen the required margin proportional to the potential gain/loss (leverage) is pretty similar to forex only difference is that you can skip and forget about the annoying pip lot mini lot and "whatever" calculation since you buy an amount of contracts and not like "100.000"€ etc and the difference aswell is that moves are bigger and stronger in range so you earn the same amount of money like in a currency trade but in shorter time.
the trends aswell are far more developed and easier to spot and easier to follow than in forex.