1- The SQLSyncProvider doesnt support out of the box SQL Change Tracking. The offline providers do. But the problem is that the offline scenario doesnt have an out of the box SQL Client Sync provider. There is however a sample SQLExpressClientSyncProvider at http://code.msdn.microsoft.com/sync/Release/ProjectReleases.aspx?ReleaseId=1200 that you can use.
2- Again, the collaboration providers whose synchronization tracking is based on Knowledge Metadata doesnt support SQL Change Tracking out of the box.
If you go for the collaboration providers which adds some database objects for change tracking and metadata, the Knowledge Metadata is taken care of by Sync Framework. You pretty much just define the scope (which columns, table, filter), provision and then sync.
If you use the offline provider (the sample provider i mentioned above), you still have to create again some tables and objects in the database.
Change Tracking only tells Sync Framework what rows were added/delete/changed, the anchor based metadata for offline providers or knowledge based metadata for collaboration providers takes care of what was sent and what was received.
3- For an n-tier solution (with WCF), you will need Sync Fx on both ends. If you have a client that could establish a direct connection to the remote database, then you only need SyncFx on the client side or where your're initiating the sync.
hth
