ilok

If the authorizations for those plugins are on the iLok, Yes.

Most plugins (not sure about VIs) seem only to check the iLok when you launch PT. Some check when they are instantiated on a track (I think Revibe does this). But once PT is booted, if all your plugins happen to be the type that only check on launching PT, you can safely remove the iLok. I'm not sure about VIs, which category they fall into, but easy enough to try, once PT is up and running, just take out your iLok and see what happens, worse thing is you'll get a message to put it back in I would guess.

No you don't I tested this some weeks ago, once the plugins are launched you can unplug your Ilok - it's a passive not active system. However you must plug it on every time you insert an Ilok enabled plugin.

If the plugin vendor supports iLok as well as 'serial number' or 'challenge/response' authorization then usually you can change your method to iLok. For instance, Audio Ease Speakerphone, and Izptope RX support several methods. If you choose iLok, you typically won't be able to authorize with any other methods. But not even VI or plugin supports iLok. Kontakt for instance is only a challenge/repsonse authorization, so even if you're using iLok for some things, that can't use it.