Hi,
1 - Yes.
A product with weight is a physical product ; a product without weight is a virtual product.
Afterwards there is a setting "force shipping regardless of the weight" to not perform that distinction.
2 - The "renew" part will require a subscription system.
HikaSerial can generate (or provide from a pre-set database) serial numbers but there is not for the moment a "subscription" feature. It is something we want to add in the future but we are currently busy with the development of HikaShop 3.
So before his availability, it will be easier to use an existing subscription system (you can see the integration in the documentation page, under the "intergration" section).
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.