I think no
but someone can physically take your bitcoins either taking you wallet.dat file, or exporting private keys or other way
No but if you have keylogger or malwares in your PC, there is a chance that your Bitcoins can be stolen once you connect to internet.
That's good then.
It is actually recommended that you store your BTC on a computer that is offline most of the time. A lot of us have cheap laptops that have a bitcoin wallet on them that are not connected to the internet. It is much safer.