1. does it take up resources? Not unless you are sshing in,and then it's neligable. It's not a gui so very light.

2. can you set it to not auto start? yes, this way.

$ sudo update-rc.d -f ssh remove

(or the windowsy way use gainroot then run it without the word sudo ie
$ update-rc.d -f ssh remove)

3. Start/stop using the init won't hurt a thing, and yes it is sshd (the ssh daemon) you want to stop.