Asterisk would work for the automatic dialing out / appointment reminders.
Ideally you'd want to have a script parse your feed at a set time in the morning, and queue up all these calls by adding them to the Asterisk spool. I imagine you'd have to parse the times from the feed, and assemble a spoken time. ie:
- play "Hello. This is just a friendly reminder from company name that you have a meeting"
- digits (9.gsm h-30.gsm a-m.gsm)