WAP Development Query

I would be grateful if anyone could help me with the following query. Thanks in advance.

First, the overall set-up. We have an Apache web server running on a HP-Unix server. PHP is also installed and is working fine. A backend database is also being accessed but this doesn't really matter in relation to my overall query. All of these components currently sit behind a firewall and no access is allowed from outside the firewall. In short, all of these elements are working fine and we can browse web pages anywhere within our own network through the Apache server.

We plan to make our server accessible to the outside world via our firewall so that we could access our pages externally over the Internet. So far, so good.

However, we also want to write small business applications predominately for use on mobile phones. We plan to use XHTML Basic as our markup language. Do we need other additional components like a WAP Gateway (or do we simply register our applications on the relevant WAP gateways in our own country) in order to deliver these pages to mobile phone users? What practical methods are used for authenticating users (given that we only want our own users to have access) that access our applications from mobile phones? Also, what is the best method of testing applications, simply log in with a phone or are there any emulators that we could use during the development stage?

I would appreciate any general enlightenment in respect of the above questions. Thanks again.