Once you reach 10k rep, which I think is where you can review flags, can you flag or not? Because it seems pretty silly if you can...
Yes, you would still have the ability to flag when you hit 10k, however, the system does not allow you to review your own flags.
Reviewing flags is mostly a privilege gained by winning a moderator election – and not by reputation. There once was a flag queue for 10 k users but it was abolished a few years ago.
The only exceptions are:
- not-an-answer and very-low-quality flags, which send posts to the low-quality queue, where you can review with 2 k reputation;
- close flags, which send questions to the close queue, where you can review with 3 k reputation.
The only privilege related to flag handling that you gain afterwards is that your deletion decisions in the low-quality queue have a stronger impact once you reached 20 k reputation.
Either way, you cannot handle your own flags or flags on your own posts.