get the small size/weight servo and receiver.
JR/KO makes very good noise fillitering 27/75Mhz receivers. 2.4Ghz I would go for SR3500 by spektrum.
Futaba S9550 is low porfile and the popular one, but a bit slower(to my sense). Sanwa/airtronics ERG-VR is super fast but bigger heavier. I use S9650 with S9257's gear set(only 26g), but it requires some mod on the mounting, too. as for streeing any servo has about 50oz of torque is more than enough. aim for the speed and weight.
you got the nice goodie as start already, keep it up!
TA05MS, F201, F103GT, RS4 Mini, TopForce (original), Mini Inferno, **Tamiya BMT 931 K4** "I am a new soul, welcome to the new world, so proud to joint the TEAM MORON. lalalala" We love Onions products, so touching. COL - cry out loud