Yeah, my issues with the 11th-Doctor Moffat era have nothing to do with his use of temporal paradoxes and non-linear storytelling (I refuse to say the T-W word.) ;) It's extremely difficult to do that in an RPG, where I can't control the main character's actions or chance. So, I'm using this point of campaign set-up to have a go.
But I'm not going to engineer a TPK right out of the gate. We won't end if you do nothing. Failure is always an option. :)
Axander: Yes, you don't have to complete it now, or even reveal the plan. In fact, you'll probably need the intervening campaign to consider it and learn more about what else is going on (the odd things missed or overlooked in the current adventure). If anyone has a specific idea, run it by me privately so I can work it in or prepare it. Otherwise, just do something dramatic: stand and looked shocked, fight the Daleks, dive into the Exterminator...
BTW, you noticed the decreasing number of scientists and Stirix's disappearance and reappearance in a different capacity. It shows that you already would have been (temporal grammar) struck by the Temporal Exterminator, and that the broken time-line fluctuates. (My original plan was to remove any PC who disappeared in this way. One RTJ was abandoned at the proposal stage, so you've already lost one fellow time-traveller... ;) )
The Dalek guns do 4/L/L and both Tarys and Bluetooth got the 4 damage. To see what that could be, I checked the wiki at:
http://tardis.wikia.com/wiki/Dalek_gun
"The Daleks' Masterplan" apparently makes it like being struck by lightning, leaving electrical burns and charring. The other information from later stories seems to support that. It seems that if a Dalek gun doesn't kill outright, it leaves a typical energy weapon or electric burn. So that's what I described when Tarys was hit, and I repeated that with Bluetooth. Plus, I was going with a 60s Dalek aesthetic. :)
Of course, a lost story from the 60s isn't at the forefront of many a fan's mind. :)
Ian's legs were paralysed in "The Daleks", but that could have been a stun setting.