"I just thought this group might have a reliable rule of thumb which could be used to determine whether income was revenue or capital, whether buying and selling is trading or investing."
it really depends on the circumstance of that particular entity, and how it has been structured. There is no simple or quick explanation for that. However, there are rules regarding whether the entity is carrying on a business or not. This issue has been discussed quite a few times already in the past few months, including some contributions by me.
If you are serious about setting up properly a structure to achieve your objectives, your best move would be to discuss with a tax accountant in a more intimate environment.
