Let me add a few things to the info already posted.
2. If I move the servo arm linkage in as far as possible, to the arm's innermost hole (next to the servo spindle), I can get closer to the desired 1" setting. Should I do this before attempting any computer EPA/dual rates adjustments? (Putting the linkage right next to the spindle seems like it would give very little power to the control surface.)
Yes, keep the linkage on the outermost hole on the control surface and move to the most practical innermost hole on the servo arm. Although it may seem to you that moving out on the servo arm would give more leverage, it is actually just the opposite. Always keep the servo arm as short as possible. This allows the most movement (resolution) and highest power. Lets look at resolution using some arbitrary numbers. Lets say the servo can move to 256 distinct possitions from center to each endpoint. Now when you set the end point to half travel it can only travel to 128 different positions. Set the end point to quarter travel and it can only move to 64 different positions. Set it low enuff and you might start seeing it just from position to position as you move the stick.
3. Is the EPA set as a % of the regularly available servo arm movement?
4. If I use dual rates to set a high rate of 80% -- does that mean it's 80% of the EPA setting?
Depends on the radio and I have not used a 9C enuff to be sure.
5. Is the regularly available servo arm movement about 40 degrees each way, that is, describing an arc of 80 degrees?
Normal total movement of most servos is 60 degrees each way or 120 total. This is only achieved on some radios by going past 100% on the EPA or other throw settings to 125 or 140.
Ed M.