Nope a wallet can nearly never been hacked. Unless you get a virus otherwise you'll never be hacked.
No what makes btc really secure is the number of people actually using it AND the number of companies mining it. It means lots of powerful people have interest in seeing btc working.
Added to that that the end of btc wouldn't help anyone!
Yeah, the security and risks for the bitcoin wallet is the same as other wallets and accounts online. You should have to make the some recommended security for your bitcoin wallet which you can adopt from here in this forum as well as from bitcoin wiki.