Welcome to "the stolen staff", which will be my third adventure as a DM here in the L4W boards. It's a published adventure and it may be a bit long by PbP standards, though it's normally a bit short for regular play.
We'll be using the Malenkirk conventions for combat, which in short means that all the enemies will be acting in the same initiative count. Player initiative is only mportant for knowing who goes before the monsters; otherwise, whoever posts first goes first in a given round, with the caveat that you can only benefit from a condition inflicted by a pnother party member once, no matter how the acting order is shuffled.
Additionally I encourage you to speed up combat by making the neccesary rolls that may result from your actions, even if someone else or the DM is supposed to make them. For example, you may move an enemy over the edge of a cliff - this normally requires the DM to save for it to determine if the monster falls down or just prone, but in this case you should make the save yourself.
If you have any question don't hesitate to ask them