There are two settings for this, one of which is how long you have to ninja edit, currently set to 10 minutes, and how long you can edit with the edits showing, currently 1 hour. These can be set to whatever the community wants.
The trust levels are pretty well documented on the Discourse site, and they can also be configured however the community chooses. Right now all new users are being granted Trust Level 2 because we figure anybody currently signing up is already an established poster. Presumably this will be turned down to much more restrictive levels once we have most of the existing users here.
There is a longer conversation the community probably needs to have about TL3 and 4. The former allows privileges that we may not be comfortable allowing people to reach just based on posting patterns. The latter is a mini-mod that may not be used at all.