Pete
Best be guided by the tube limits,
https://www.g8wrb.co.uk/data/Eimac/4CX1000A.pdf, or the Acom 1500 documentation.
The 10mA plate idle current seems low if you are running in a linear mode, eg AB1, but is possibly correct for some other non-linear mode eg CW.
The RF drive should be reasonably consistent across all bands if the input circuitry to the tube is properly designed and tuned.
Whether the 9W of RF drive is consistent for that output power is the real question...
One Youtube video on the 1500 indicated about 13dB power gain on 7MHz so that means that it should provide about 180 watts (13dB above 9 watts) out. Getting approximately double that indicates a power gain more like 16dB and your front panel display gives you the real/actual gain value.....
Doug