1. Yes, that happens, although constitutes around 10-15% of work being done.

2. I am certainly listening to any suggestions, but don't necessarily actively encourage it before proposing a solution. Perhaps this is a direction I need to move towards.

3. Mostly yes, as overwhelming part of the complexity just comes from knowing how various parts of the system interact. From time we have an open-ended 'research' (where the outcome is not known upfront) project, but these have a very mixed success rate and tend to overextend the time budget.