You only need one high-torque digital on the rudder, like that 5955, 8711, or Futaba equivelant. It will be more than enough. You don't need a choke servo at all and don't need a servo for the killswitch if you go with a Smart-fly, RCATS, electrodynamics, or similar electronic kill (I prefer the Smart-fly). These types of kill switches, or at least the Smart-fly, are lightweight, solid state, fiber-optically controlled(means no ignition noise can be transmitted back to the receiver), and will kill the engine if you lose total receiver power. The same can't be said for a choke servo or servo-operated kill switch

The receiver can easily handle the servos, that's not what you need to be concerned with. What you need to be concerned with is providing enough power to them. One switch with one plug going into the receiver is NOT going to be enough. You need a minimum of two power leads going into the receiver, and I recommend more. I am running 8 servos total on my 35% into a total of 6 ports on my 10 channel receiver, plus my Smart-fly ignition kill. There are 4 remaining ports and they are all filled with power leads from my batteries.