is there a way in Oracle DB (regardless of version) and by means of views or traces/logs to retrieve info for a version upgrade (for example the timestamp it took place, prior versiof of database and current-upgraded version)...?
You might be able to look in the DBA_AUDIT tables (if auditing is turned on) to see when the system tables and such were updated during the upgrade. Other than that, I don't know of any place that it would store previous version information and timestamps as to when that changed.
You could take a look at the Oracle binaries on the actual server to see how old they are. This would give you somewhat of a timestamp as to when they were upgraded. It depends on what you're looking to find; last upgrade, date of previous upgrades, etc...