static ip to a swicth want to use local sql server for web

A) You have one single static IP, and a router with NAT?
If so: use static ip also on the intranet. Use local DNS server, or simply NetBios names of the server.
B) You want to publish the SQL service to the internet?
Dont do that! Allow only the front-end (web server) to be accessed from outside, and only the http ports! Dont use the WAN IP on the LAN!
Answer to you questions:
1) you can use the IP address as you would use the hostname in the connection string
2) I dont understand. Please be more precise.

Second interpretation:
You have a web server outside your LAN. And you want to access the SQL server from the web server via your router?
Well... that's not a good idea. You can do it with port forwarding and so on, but this is not the way. There was a http binder in SQL 2000, but I think there is no more.
But you can concentrate all you business logic inside your LAN, and publish a WCF or other kind of service via https to your frontend. But you should leave only the presentation layer in it.