Groovy Google Calendar, but multiple phones and scheduling to same calendar?

I’m helping out my friend Rob set up the computer aspects of his Chiropractic practice. One thing he wants is to view the client schedules for himself, his business partner Keith and the various other treatment rooms at his office. He doesn’t want to spend the money on an Outlook Server to allow OWA. So we’ve been exploring Google Calendar. It’s great in many ways but a few things I still haven’t figured out:

• How can one customize the event entries to contain more information? For his practice, Rob would also like to annotate appointments with copay amounts, whether the patient showed up and other pertinent information. It would be nice to not have to place this in the generic textbox field. Instead let me generate various templates for calendar events and specifically the fields that each different template contains.
• Both Keith and Rob would like to view and schedule events in the same calendar via their phones. OK I’d like this because it’s cool and could be useful. It’s clear that a phone can subscribe to multiple primary calendars, but can multiple phones subscribe to *one* calendar? A simpler example would be a husband and wife sharing a gmail account and the calendar. It might be sufficient for Keith and Rob to consider the primary calendar read-only but allow scheduling from their connections at home.
• Can an appointment scheduled via SMS be rejected via SMS if there is a conflicting appointment? I’ve tried to set “auto-accept invitations” to “Auto-accept invitations that do not conflict” but that option in the calendar settings is not available on the primary calendar. I would love it if I could change this setting but also specify that it should be confirmed if there is a conflict and the event is scheduld via SMS. If I’m scheduling directly from the Google interface, I’d like to configure it so I’m not asked to confirm if there is a conflict. You can see how these features would be particularly useful for Keith and Rob.
• If a single phone can subscribe to multiple calendars how can it pick a particular calendar to schedule an event on via SMS? Perhaps a discriminator to select a particular calendar that the SMS is targeting. For instance SMS to GVENT: “cal me tomorrow at 7:30 workout with trainer”. Let’s assume that I’m married, SMS to GVENT: “cal us Thursday 6pm dinner with Liam and Susan”. The notification feature for a calendar should allow multiple email addresses (or you have to create an alias).

Perhaps I’m blind and it’s out there.