Local Sync Store - questions

I want to sync 4 DT batabases. 2 of the databases are currently on Mac1, the other two on Mac2. I want all the four databases to stay in sync between Mac 1 and Mac 2.

How many sync stores do I need to create? I suppose one single is enough?

Where do you recommend to put the sync store? On Mac1, Mac2, on a NAS accessible to both Macs?

Please see this: Sync Store question for 2.9

Also, where you store it is also a matter or preference. (And our new Sync engine is more flexible than Sync 1.)

Is the contents of the local sync store compatible with Time Machine backups? I.e is Time Machine able to correctly read the changes within a sync store?

TimeMachine should have no problems backing up a .dtCloud file (current) any more than it did a .dtSyncstore (Sync 1)