Michael W. Ryder said:
Is there a maximum cable length for direct connecting?
90m is the spec, though in practice it will tolerate about 120-150m in good
conditions.
One security issue with wireless, as you correctly identify, is that most
routers have it turned-on but unencrypted as-supplied to make initial setup
easier, thus an accidental router hard-reset or NVRAM fault may leave it as a
public connection. Exactly how much risk this poses is open to question. If
the NVRAM has defaulted then the Internet connection won't work, although any
internal computers with unprotected shares may be at risk. Chances are the
fact that the Internet connection has stopped working would be noticed before
an intrusion occurred.