You can also use Events to get requested data:
SELECT e.* FROM Events e JOIN EventTypes et ON (e.EventType=et.EventType)
WHERE et.Name IN ('Node Added','Interface Added')
But if you are able to get all requested data depends on how are your events/auditing retentions set up.
For interfaces you should be able to get the date of the first traffic poll:
SELECT i.FullName, dat.added FROM Interfaces i JOIN
(SELECT MIN(DateTime) AS added,InterfaceID FROM InterfaceTraffic
GROUP BY InterfaceID) AS dat
ON (i.InterfaceID=dat.InterfaceID)
Jiri