The switch he is showing is for the receiver power(on the truck) not for the transmitter. Yes they come with on/off switches, just so much talk maybe confusing.
As far as throttle return springs, the 18ss doesnt require them does it? And for that reason, aren't available as a direct replacement part. Assuming you are talking about the ss kit. The rtr doesnt either. But if you want one anyway, the savage with s-25 does use one. http://www2.towerhobbies.com/cgi-bin...?&I=LXDLJ4&P=Z They may be a little long, but could easily be modified to fit.
By the way, got my savage in today! Unfortunately it's supposed to rain for the next couple days.[]