If you have lots of coins in your online bitcoin wallet,will posting that address in public like forums,facebook etc make it more vulnerable to hacking?
1.Should such addresses be kept secret as much as possible to keep them away from hackers eye?
2.If kept secret,is there a way for others to know how many wallet addresses holds big amount if bitcoins?
If you have lots of coins in your online bitcoin wallet,will posting that address in public like forums,facebook etc make it more vulnerable to hacking?: Yes, just as posting pictures of a stack of gold or a box of diamonds will increase your odds of getting robbed. You are essentially making yourself a target. Someone could want to hack you now who previously wouldn't have known.
1.It depends on your privacy and storage techniques but usually YES
2.They will still be on the blockchain so technically yes.
Nice, okay. Could you please explain how posting a public key would increase its vulnerability? - have you got an unknown method of spawning a private key from a public key?
Why bother...
No it want increase its risk of getting stolen. You need to worry more about the trust between you and your wallet provider. No online wallet is hack proof, but levels of mitigating attacks do vary depending on your provider. Right now, blockchain.info is the only 99% provider that I've seen. They if I remember correctly, they give you the KEKey (key encryption key)