This means I’m TS eligible, correct?
Since it’s obvious T3 isn’t always synonymous with Secret, will job searching sites/employers eventually go the route of looking for employees with T3 and T5 instead of Secret vs Top Secret?
Probably not since the Tier system is subject to change. Also, Secret and TS are more commonly known terms.
Yes.
If your employer decides tomorrow they want to put you on a project that requires TS access, they would be able to flip the switch and upgrade you administratively without having to re-investigate.
That would not be the case if your investigation was only a T3.