4G Backup

Hello

I manage IT for a volunteer fire company.  I have noticed occasionally we have some outages, esp during weather incidents. Now I understand these things happen, so I'm not trying to blame Comcast. Our mission critical operations come over POTS telephone lines with a proprietary wireless backup. 

I received an email from Comcast about 4G backup.  I'm interested in this, but unfortunately, they don't provide a way to email to get answers. I hate businesses who force you to call them, so I'll ask here my questions.

1.) Is the data unlimited or is there a limit on how much you can use? I know the speeds aren't equal, but would we be capped at 1GB per month, per outage? 

2.) It says 29.99 a month, does that include the modem? If not, how much is the modem? Is it possible to buy a modem? 

3.) Has anyone used this? Is it worth it?

4.) Is it possible to block certain websites when on the 4G? I am an IT guy by day, and I know that a single 4G modem isn't going to be able to handle 5 people streaming netflix, 5 streaming music, 10 browsing the internet, and also power a VoIP trunk line.