Sorry for the LONG delay. We've been swamped in December and have some staff away. Feel free to email or call us direct anytime you need an quick answer to something.
>1. The website comments add-on is capable to work (maybe some modification) like a basic ticketing system?
Yes, but there's a LOT more required for a ticketing system. Best place to start is with a list of bare-minimum requirements.
>2. Any update when the HTML5 uploader is finally embedded in CMSB? (maybe with ability to use this function from front-end as multi-file uploader as well)
This is the current major feature rewrite we're working on for CMSB. It's annoying for us as well. Once we get it working we may add it to Form Generator plugin soon after.
>3. Any update when the signup/login add-on based on FB Account-Kit will be available?
Not public release date planned, but email me direct and I can get you setup with something.
>4. Do you plan to make Holiday Sales on add-ons this month?
No plan for a sale related to addons, no. Just the CMSB sale: https://www.interactivetools.com/order/?CMSBUILDER=1
Hope that helps! Let me know any other questions.