If you do have a business account with static IP, that IP will not be relayed to your network firewall as the HT2000w is a combo Modem/Router unit that can't be put into a bridged mode. The best you can do is treat it (the HT2000w) like a normal consumer grade router and forward a set of ports, upto 10 maximum, to your network firewall and then forward again there if you need remote access to the network.
If you are going to configure the WAN interface of your SonicWall with a static IP, you would be best off to get the MAC of the WAN interface and setup a static address on the HT2000w and then put in the same parameters on the firewall that you entered into the HT2000w.
By default your HT2000w will throw out a 192.168.42.0/24 address with it as the DNS server to devices connected to it.
If you need a guide for basic port forwarding instructions, I have a short simple one at my website: HT2000w Port Forwarding
It works, is it ideal? No. But, it's better than what we had before, which was zero remote access.