Elastix's Developer addon

Currently have a php application running on an 3rd party server that shows names and phone numbers of potential cusotmers. We also have Elastix running on its own Linux pc to run our PBX phone system. We would like to A) add the ability to click on a phone a phone number in the existing PHP application and automatically dial via the Elastix PBX the phone number. B) once the person is on the phone and hears a answering machine, this person on the phone should be able to click on the screen "leave voicemail 1, or 2 or 3, etc" and the system would play a pre-recorded message, but it will not require the person on the phone to stay on the call while the message is being played. this can save lots of hours for the person making calls all day long. For example, I am dialing a corporation, I dial through the corporation PBX system, get to the directory and find out the extension for my potential customer. 9 out of 10 times we will get a voice mail "thanks for calling John, please leave a message", then we would like to say "Hi John"... click which voice mail message we want to leave and Elastix would play the pre recorded message. we can immediately go to the next call and save 60 seconds per message we don't have to hear.