Tested with the current Steam Beta 1.3, but no real Beta issue, as I encountered these in earlier versions (my first walkthrough).

"Follow Austin"

Requirement for the main questline "Hole in the Wall" for this Vault. You may have to follow Austin on his tour around the Vault. Sounds easy, but when facing him, you almost constantly switch into "dialogue" mode, which freezes all directional keys (aka you cannot move). This fixes itself if Austin is farther away (outside dialogue range). Unfortunately this usually causes the quest (item) to fail. There is even a workaround: Move without facing Austin.

Which is difficult in some cases, as he wanders around obstacles which is a bit of a nuisance when e.g. walking "sideways".

Apart of that if facing Austin the character sometimes does the usual dialogue mumbling (when hitting keys during dialogue) like a mumbled "Shut up" - which seems out of place here.

Some quests do not start after main Valut 81 questline

Completing main questline seems to lockup several mini quests within the Value, e.g. telling a story to the class (the teacher will not start the quest after you have completed the main questline within this Vault, that is deliver (or use) the cure).

Any assistance will cause infection

After starting "Hole in the Wall", any additional character who helps you fighting of the infected mole rats will most certainly cause you getting infected, too.

While I read about the issues using followers (and therefore leaving my follower behind), I wondered why I still got infected. Curious readers might not know that you are able to avoid infection if no mole rat bites you.

This bugged me until I found out that the Protectron you are able to activate in the early part of the Hidden Fault will cause you being infected if that Protectron is bitten by a Mole Rat (which will happen in 90% of all cases within the Maintenance section).

On one side it might be logical that a allied Protectron counts towards followers, on the other hand if you want to avoid infection by notmal means, that Protectron is rather useless (as it only covers the beginning of that level).

Sending Dogmeat home

Avoiding infection caused me sending Dogmeat home (to Sanctuary Hills). I would guess the dog would walk towards the beginning of the level (where I got into the Hidden Vault).

Interesting enough, Dogmeat begins to walk all through the level. There is a certain position within the Vault where you are separated from Mole Rats by a closed (but unlocked gate). I was a bit surprised that Dogmeat reached that point some time after me and just opened that gate, letting all mole rats in. I know, these Mole Rats might dig themselves to certain points on your side of the gate but it is one thing to wait in front of the gate and another onother topic that someone opens the gate in your back...