Yes to the wget command above.

The difference is that the development version is, as the name suggests, in development. Once a bug is found, it is first fixed in the development version and then later backported to stable.

On the subject of defending against DDOS, its more down to the firewall than the webserver when trying to mitigate attacks. If you are really worried about it, then you should consider hosting that can provide DDOS protection.

Chances are though, you will never be faced with a DDOS attack.