1) Yea, you can have extra ships in your sector without them being towed. If you want to make use of the IC ship, you'll have to be sitting in it all night.
2) Only if the sysop has turned off duplicate IPs. All your machines on a LAN will have their local IPs NAT'd, and their outside IP the same. To the sysop's game, it'll look like all of your boxes have the same IP.