I've ran between 2 and 12 players. My normal game group is 6 now for Earthdawn Cathay Quest. Our 50 Fathoms group is sometimes 7 players with Ted as GM. I'm usually comfortable at about 8 or so.
Initiative: Use playing cards for it. The jumbo ones work the best. Once everyone rolls Initiative have them place the card numbers with their Initiative face up. For say 20, use a king and queen for example. The highest card goes first. Reserve an action by moving the card 90 degrees. Once they act, have them turn their cards face down. If they get an Air Dance attack, give them a joker to remind them to place on top of their downed initiative cards. For your monsters, take their Initiative Step and place it on the table. Flip it down after they act, then flip it back up on the next Initiative phase. This allows you to concentrate on the declare action phase and not worry too much about Initiative.
Resolve: Its a lot easier to use the EDR table than previous editions of Earthdawn. The table is simply All 1s, Poor (x0.5 Difficulty Number), Average (DN), Good (x1.5 DN), Excellent (X2 DN), and Extraordinary (X2.5 DN). So a 7 DN would be 1, (3.5) 4, 7, 14, (17.5) 18. I say its easier since double the DN is the Armor-Defeating Hit (without the deflection bonus exceptions anyway). If a character is taking too long for their turn, have them go on hold by moving their card 90 degrees and move to the next person ready to act.
Poker chips: If using a map and miniatures, use small Axis and Allies poker chips underneath figures to remind you of conditions like Harried.
Another thing you can do is use a stack of poker chips to keep track of karma for any Game Master Characters/Opponents you are controlling.
Have a piece of paper handy for keeping track of total damage.
Make your players control any of their Game Master allies in combat, it frees you up to concentrate on the baddies.
Have an overall plot arc, a goal for the players to achieve at the end. Goalless games get boring fairly quickly.
Look at my blogs to get some extra Game Master Characters to use.
Never Unprepared (The Complete Guide to Session Preparation) just went Platinum on DriveThruRPG. Made by GnomeStew's writer Phil Vecchione (Gnome Stew is really good too).
http://rpg.drivethrustuff.com/product/1 ... ssion-PrepThe Book of Roleplaying Hints, Tips, and Ideas was a good read. The biggest tip from it is MOP. Motivation Objective Personality for character design. Especially for Game Master Characters.
http://rpg.drivethrustuff.com/product/1 ... -and-Ideas