* The question of tactics and Initiative order is an interesting one. What I've seen in all of the 4e games I've GMed is that its something like this (I'll use the encounter that you quoted above and I'll simply use a Fighter as an example).
PRE-INITIATIVE: The Fighter player is considering each of the following possible moves for round 1:
1) Weave between the Lightning Pillars and get to the NPC and start the process of breaking it out of the machine; Run (Move +2 but give up CA) > Mighty Sprint > Standard Action Athletics Check to sunder the machine > Action Point Heal to mend the ailments the machine is causing the NPC (hoping for 2 out of the 4 required successes by round 1). Invariably, this would change the situation of the Skill Challenge with the machine possibly having countermeasures it can deploy (steel tentacles perhaps?) that the Fighter would have to withstand/defeat next round.
2) Force the Mad Scientist (MA) into melee it can't escape (hopefully preventing it from getting to the rune to teleport to a Pillar); Run > Run > Mighty Sprint (which includes a buffed Athletics check to leap and climb the pillar to the balcony to get adjacent to MA > Action Point Seize and Stab Daily Power for big damage to the MA and to Grab him which he can't get out of until the END of its NEXT turn. The MA would be damaged + shut down hard with that Grab for multiple ROUNDS with this effect and Combat Superiority (its ranged attacks would yield OAs) and it wouldn't be able to get to the Teleportation Rune + Marked (subject to all of its effects) + subject to Combat Superiority (making getting away a virtual impossibility unless it can Force Move the Fighter away from it or teleport from where it is).
3) Get to the nearest Lightning Pillar to kill the two Flesh Golem Minions that have just been animated by the Pillar and then sunder the Pillar; Run (hopefully avoid the Lightning Damage when the Fighter gets in proximity) > Standard Action to Cleave (a hit on the first one and the 2nd one is auto-swept with the Minion Sweeper rider of Cleave) > Action Point Athletics Check to Sunder the Pillar and destroy it (shutting off the ability for the MS to port there, shutting off the Minion activation, shutting off the proximity Lightning damage).
4) Get to the East Entrance to man the 15 foot opening (which, with Combat Superiority and a 3 SQ opening, the Fighter basically becomes an impenetrable wall that anything that comes from that corridor would die upon) that the Iron Golem is in and engage the Golem; Run > Charge the Iron Golem as a Standard Action Attack (and decide if they want to use Bull Charge Encounter Power - Damage + Push + Shift Adjacent + Secondary attack for Prone - as you can sub it for a Melee Basic Attack). Creature is at least Marked and subject to Combat Superiority (as above) but probably also damaged + Pushed into the corridor + Fighter adjacent + possibly Prone. If the Golem is Prone, the Fighter may then decide to Minor Action Mighty Sprint to get adjacent to either a Lightning Pillar and Sunder it or get adjacent to the pair of Flesh Golems underneath it > Action Point to Athletics (Sunder) the Pillar or Cleave the Flesh Golems.
This whole turn would possibly leave the following scenario in its wake; (a) that Flesh Golem damaged by around 1/4, (b) basically useless for round 1 (as it would have to spend all of its action economy to get up from Prone and move into the room), and (c) either both Flesh Golems under the pillar killed or the Lightning Pillar destroyed.
As I look at this decision-point and the possible action declarations it could yield, I see (a) extreme diversity, (b) significant effectiveness in tipping the scales for the good guys in each outcome, (c) different mechanical interactions, (d) different amount and type of resource investment.
The only thing Initiative order might do is change the final formulation of the 4 decision-points up top a bit (which one they finally decided to prioritize), possibly removing 1 or 2 and opening up another 1 or 2. For instance, if the Flesh Golems goes before it and they become spread out, that would limit the Cleave aspect of (3) above.