I am wondering if Rainlender supports these features:

1) Subscribe to another persons calendar via LAN / Internet. For example, at home or at work, one person can subscribe to see the events another person has entered, for sharing / planning.

2) Synchronize to another Rainlender database, for example, if the program was installed on a notebook computer, the user may want to sync back and forth with their desktop PC.

1) Yes, if the calendar's ics file is published on a server which is accessible by the application.

2) Yes. You need a server where the calendar file can be stored though. You can also use Google Calendar as the backend if you don't have your own server.

Great, thanks. One further question...

Can these network located calendars be accessed even when intermittently online, that is to say, a LAN or Internet connected source may not always be available, but allowing the calendar to persist and be readable would be useful.

Yes, there is option to keep an offline copy of the calendar so you can access it even when you are not connected.