So the application status online will not change at all until you actually receive a decision letter (my experience from last year after being dinged post-interview).
Interviewfest has a lot of activities, but most of the admissions committee is locked up in the interviews all day up in the LGO office space which is adjacent to the LGO lounge, so don't expect to be gaining any extra brownie points with interviewers at the events haha. Though, there will be non-interviewing members that will be around. For example, last year, Don, the previous head of LGO that retired, was mingling with prospective students, as was Jane D (admissions director) - they were not interviewers but I am pretty positive they sat on the committee when it came time to make decisions.
For those without interview invites yet - don't fret! They may not be finished evaluating everyone completely. For example, if you are "on the bubble", they are probably keeping you around and are going to see what happens with interviewfest, so don't lose hope. Immediately after interviewfest, they will have a good general impression if they need to send more invites out or not before individual decisions are even made.
Best of luck to you all. For me, hopefully second time is the charm, or else I guess I'll be back here next year!