> Should I be creating a "global" DataContext object that I use from
> within each of my WCF operations, or should I create a DataContext
> within each operation?
I would argue "local" - there are lots of issues otherwise, not least
> 2) What is the right way to pass data to/from WCF operations?
> Is it possible to return the entity classes from an operation?
I don't really understand the question - perhaps re-phrase?
One common approach here is to keep both the original and new version
(at the client) - send them both up the wire and use the overload that
allows you to add them to the data-context; this enables change/conflict
Alternatively, look at ADO.NET Data Services (aka Astoria), which does
all this for you - i.e. it provides a client data-context that can talk
to your IQueryable<T> service over WCF.