Hi,
1. Yes
2. The licence limit the support, the auto update system and the cron task system to one website. Basically, all the services we provide with the commercial editions.
3. For HikaSerial and HikaMarket, we don't have a multi-support license yet, so yes, it would require the purchase of another license.
However for HikaShop we actually published a multi-license edition called Multisites which does exactly what you're talking about:
www.hikashop.com/extensions/hika-essential.html?product_id=201
We're still working on modifying our website structure to accomodate it and will probably publish similar editions for the other extensions next year.