Since the mid 1980’s all servo connectors had the same pin orientation except Airtronics. In the ‘90’s they changed to the industry standard. Tooth Dr. is correct that the only thing needed is to trim off the connector tab and the servos will work just fine. The one thing that I highly recommend with Spektrum gear is to use a 6V receiver battery. There were some issues using 4.8V nicad packs that when under load the voltage dropped below the RX operating voltage and the RX had to reboot. The RX itself will handle up to 10V but some servos will not handle more then 5V. Your Futaba S148 servos will be no issue but most of the newer Futaba 3000 series servos are 5V max. My choice is what is referred to as a LiFe 6.6V battery. You could of course go with a 5 cell nicad or nickel metal hydride.The 3000 series servos would need a regulator to step the voltage down to 5V.

Gyros, the description of function that Hydro gave is mostly correct. If the airplane pitches upward it will automatically feed in a down elevator command. Same with roll and yaw. Typically used on the very small UMX models that otherwise would be unflyable. I have owned a couple myself and they were great fun. However the old mechanical gyros are long gone. They are now based on a piezo ceramic crystal that is able to sense the earths magnetic polars and the difference of the magnetic forces at different attitudes. They must go through a short calibration with the model level prior to each flight.