1.) SSH is the ability to access the iPhone's filing system over WiFi and meddle with it. If you don't want to meddle with your iPhone via WiFi like this, then turn it off. It will not automatically come on, but unless you deliberately want to use SSH, there is no reason to have it active.
2) It will waste power still. While it may not tell you it has detected other networks, it is constantly searching the environment for what is there, and if your home one is there, it joins that network. Best to turn it off unless deliberately being used.