If you select the "Activate all Cylon ships of one type: Heavy Raiders" of the Cylon Fleet location, do the Centurion already on the Galactica move?

Ouch... in a game with 3 Cylons (6 or 7 players) if a Centurion appears on the Galactica it's almost like an auto-win for the Cylons.

Ouch... in a game with 3 Cylons (6 or 7 players) if a Centurion appears on the Galactica it's almost like an auto-win for the Cylons.

Only if they all have turns in a row. And even then, you just have to make sure you deal with any Centurions before the three Cylon turns come up.

Personally, I've never seen a Centurion victory where the Centurion was pushed only by Cylons. Cylons have to get pretty lucky, or Humans have to be not paying attention for it to get within automatic loss territory.

In the last game maybe the 3 humans have been very unlucky, but with a total of 5 rolls (2 of witch with a +2) the single Centurion wiped out them all.

You'll get five misses out of five rolls, two of which using Strategic Planning, on average every ninth or tenth game. So, pretty unlucky, but not exceptionally so.

Not quite - the numbers do add up to about a 10.5% probability of those rolls failing, but there's more to it than just those numbers. To be more precise, that sort of loss only happens every ninth or tenth game in which a Heavy successfully reaches Galactica before the fleet jumps, you can't make more than five Armory activations, you can't Strategically Plan more than two of them, you can't use Helo's OPT, Kat's OPT, or Anders's OPG, you don't have Calculations available, and you can't use Authorization of Brutal Force. That happens a lot less often than once every ten games; I've played a good thirty or so games of Battlestar Galactica (with varied amounts of expansions), and yet I've only ever seen humans lose to centurions once (and that was due to three centurions getting on board at the same time, not due to several failed rolls against a lone centurion).

I've seen Centurions take out Galactica several times - either because humans didn't take the threat seriously until too late, or because several threats all hit at once, and humans couldn't focus their attention on the boarders, or because several boarded in quick succession.

Authorisation of Brutal Force or Armory is a strategic decision - on the one hand, the Quorum card offers a guaranteed kill; on the other, it risks Morale, and requires the President to either have the card in hand, or have drawn enough Quorum to make it likely to come up in time.

Not quite - the numbers do add up to about a 10.5% probability of those rolls failing, but there's more to it than just those numbers. To be more precise, that sort of loss only happens every ninth or tenth game in which a Heavy successfully reaches Galactica before the fleet jumps, you can't make more than five Armory activations, you can't Strategically Plan more than two of them, you can't use Helo's OPT, Kat's OPT, or Anders's OPG, you don't have Calculations available, and you can't use Authorization of Brutal Force. That happens a lot less often than once every ten games; I've played a good thirty or so games of Battlestar Galactica (with varied amounts of expansions), and yet I've only ever seen humans lose to centurions once (and that was due to three centurions getting on board at the same time, not due to several failed rolls against a lone centurion).

I still think that game-over by Centurions is too "wild". If you are lucky Centurions do nothing.
If you are unlucky you waste a lot of precious actions and you still can fail...

Of the six Cylon victory conditions, the resources are attritional - they gradually decrease over the course of the game, and are usually only an imminent threat for the last couple of jump cycles. Galactica damage or Centurions can end the game in fairly short order at almost any point - meaning that there's potential for tense moments even in the first jump cycle rather than all the threats being "If we fail this check, then we lose one of our seven remaining morale! We have to pass, or the game will get slightly harder to win!"

Damage can be repaired with cards (a wise human will keep some repair cards ready).
Heavy Raiders can be destroyed by Pilots with the right cards (Maximum Firepower is the best one).
Centurions... you get to roll. Yes, the +2 to the die roll is your friend, but there is nothing specific against them (as opposed to Heavy Riders)