Newbie trying to understand how this works

Hi everyone.
I know both my Subject is very obvious and repetitive, but after a whole week of researching, reading forums, reading news and even a book about bitcoins I still have some questions regarding how to buy bitcoins.

The way I started was thanks to my brother, who started investing with bitcoins in 2011 and since then he's been poking me to do the same (unfortunately I didn't listen to him until last week). He gave me 0.5 bitcoin last week so I decided to give it a try bought 0.1 bitcoin through coinbase.
The thing is that I would like to know if there is "simpler" electronic mean of buying btc.
I've tried MT.Gox marketplace but I haven't heard from them (my identity is being verified and it's been more than 10 days already).
The problem with coinbase is that since the funds are being withdrawn from my checking account, it takes almost 7 days to process the purchase, so for instance, I wouldn't have been able to sell my bitcoins (which I bought at 440) when the reached the $800 a few days ago.
I understand that bitcoins are the kind of long term investment, but still, I don't see how I could benefit from it in the short term given the high restrictions that exist to buy/sell the currency.

Another option is localbitcoins but I refrain from using that exchange for two reasons: the price for small amounts was 20/30% higher than the ones in the on-line exchanges (specially for little amounts, which is the kind of transaction I can afford). And second, I felt kind of unsure about the security of these kind of transactions. Probably this is a prejudice, so maybe someone could help me to understand the safety of this kind of operations.

So any insight about this issues would be very much appreciated!

Thanks
Cecilia