Hello everyone,
It’s nice to meet the community and hope to have best question-solving time here.

Now, I’d like to get straight to the subject.
I have the need for two Internet networks, a chilling café network and an office network.
The Internet is starting in the office via a DSL modem, configured like a router, to share Internet connection with other office computers through a simple switch.
Due to database requirements office computers must be, and are on static IPs.
In the café I would like to share same Internet connection, but via a wireless router, and I have attached that wireless router to the switch in the office.
My question is: how should I configure the wireless router in café properly, so the visitors will be able to connect to Internet automatically, via dynamic IPs?
I don’t think is normal for them in order to connect to Internet to configure their network cards manually, all the time when they visit my cool café.
Also is it possible to hide somehow local network computers IPs from bad hackers in the café.

DSL Modem is: D-Link 2500U
Wireless Router is: DI-624S - Wireless 108G USB Storage Router (http://support.dlink.com/products/view.asp?productid=DI%2D624S)

Some help is really and deeply appreciated.
Thank you very much.